GENERAL 
HYGIENE 

OVERTO-N 


GIFT   OF 


BIOLOGY 

LIBRARY 

G 


A  CLEAN  BARN 


CLEAN  MILKMEN  CLEAN  BOTTLES 

WHOLESOME  MILK  MEANS   CLEAN   MILK 


GENERAL   HYGIENE 


BY 

FRANK   OVERTON,  A.M.,  M.D. 

'AUTHOR   OF    "APPLIED   PHYSIOLOGY1' 


NEW  YORK.:.CINCINNATI.:.CHICAGO 

AMERICAN    BOOK    COMPANY 


BIOLOGY 

LIBRARY 

G 


COPYRIGHT,  1913,  BY 
FRANK  OVERTON. 

COPYRIGHT,  1913,  IN  GREAT  BRITAIN. 


OVERTON,   GENERAL  HYGIENE.  . 
E.    P.    I 


'•    *      • 

•*•  -  ' •  •  \  •  - '  : 

•--••.•-•.       ..:. 


PREFACE 

THE  personal  welfare  of  each  individual  depends 
largely  on  the  efficiency  of  his  bodily  machinery. 
The  effects  of  mental  and  moral  habits  on  the 
health  of  the  body  have  long  been  known,  but  the 
recognition  of  the  effects  of  bodily  health  upon 
the  mind  and  the  moral  character  is  of  recent  date. 
Bodily  health  is  readily  within  the  control  of  either 
the  individual  himself  or  his  parents.  The  modern 
science  of  hygiene  and  sanitation  is  founded  upon 
the  idea  of  personal  responsibility  of  each  individual 
for  both  the  transmission  and  the  acquisition  of 
most  diseases. 

The  experiences  of  sailors  and  of  explorers  in  un- 
inhabited lands  prove  that  a  small  number  of  healthy 
persons,  separated  from  the  rest  of  their  fellows,  and 
moving  from  place  to  place,  will  be  remarkably  -free 
from  diseases  and  infirmities  in  spite  of  hardships 
and  exposure.  The  preservation  of  the  same  degree 
of  healthfulness  in  the  midst  of  crowded  communi- 
ties is  one  of  the  greatest  problems  of  modern  life  ; 
and  it  will  be  solved  only  when  every  person  ac- 
quires a  knowledge  of  the  elementary  principles  of 
modern  hygiene  and  sanitation. 

This  is  a  textbook  on  the  general  subjects  of 
hygiene  and  sanitation.  It  is  adapted  for  pupils  in 

5 

304070 


6  PREFACE 

the  intermediate  grades.  It  fulfills  the  require- 
ments of  modern  courses  of  study  in  physiology, 
and  also  conforms  to  the  laws  of  the  states  requiring 
instruction  in  sanitation  and  in  the  prevention  of 
diseases.  It  is  also  a  textbook  on  anatomy  and 
physiology,  but  all  the  topics  discussed  have  a 
practical  application  to  everyday  living.  The  sub- 
jects are  presented  from  the  point  of  view  of  a 
health  officer  on  active  duty  among  all  classes  of 
people,  rather  than  that  of  a  science  teacher  whose 
activities  are  confined  to  a  classroom. 

One  reason  why  a  knowledge  of  hygiene  is  not 
more  widespread  is  that  its  literature  is  usually  full 
of  technical  terms  and  scientific  phrases  that  are 
not  intelligible  to  untrained  minds.  This  book  is 
not  a  vocabulary  of  new  terms  which  must  be 
mastered  before  a  knowledge  of  hygiene  may  be 
acquired;  but  it  employs  everyday  words  and  un- 
derstandable English  to  inspire  the  reader  to  live 
healthfully  and  to  promote  the  cause  of  public 
health. 


CONTENTS 


CHAPTER 

I.  THE  STUDY  OF  HYGIENE     . 

II.  ORGANS  AND  CELLS 

III.  COMPOSITION  OF  THE  BODY 

IV.  BACTERIA      .        .  •      .    ...»'.    . 
.  V.  ALCOHOL       .        .        .        .        . 
VI.  NARCOTICS    .        .        , 

VII.  BONES  AND  JOINTS       .        .'.      * 

VIII.  MUSCLES       .        .        .        .        . 

IX.  CIRCULATION  OF  BLOOD       .        , 

X.  EMERGENCIES       .         .        . 

XI.  RESPIRATION     ...        . 

XII.  HINDRANCES  TO  BREATHING 

XIII.  FOUL  Am     .        ..       .        .        . 

XIV.  VENTILATION     .   .        .        .        '. 
XV.  BODY  HEAT          .        .        .     :  . 

XVI.  THE  SKIN     .        .       '. 

XVII.  EXCRETION   .        .        .        . 

XVIII.  WATER  SUPPLY    .        .        . 

XIX.  VERMIN         .        ,'       \.        .     '    ." 

XX.  FOOD  ELEMENTS  .        .       ft        r 

XXI.  DIGESTION    .        .    ,     .        .       .. 

XXII.  ABSORPTION  AND  ASSIMILATION  . 

XXIII.  FOODSTUFFS          ;.       .  '    ;. 

XXIV.  WHOLESOME  FOOD       .        .        . 
XXV.  CARE  OF  THE  NOSE  AND  MOUTH 

XXVI.  INFECTIOUS  DISEASES   .                 * 

7 


PAGE 

9 

18 
28 

35 
46 

58 

64 

76 

88 

1 06 

116 

125 

134 
144 
152 
162 

i?3 
184 
197 

211 

222 
23I 
238 
25I 
263 
270 


CONTENTS 


CHAPTER 

PACK 

XXVII. 

PREVENTION  OF  INFECTIOUS  DISEASES 

.        282 

XXVIII. 

TUBERCULOSIS   

.        297 

XXIX. 

THE  NERVOUS  SYSTEM      

•        307 

XXX. 

THE  BRAIN        

•       318 

XXXI. 

THE  SENSES       

•     337 

XXXII. 

THE  EYE  

•    346 

XXXIII. 

THE  VOICE        

•    357 

XXXIV. 

PUBLIC  HEALTH  AGENCIES        .... 

.    361 

GLOSSARY        ......... 

•    369 

INDEX 

170 

GENERAL   HYGIENE 

CHAPTER  I 
THE   STUDY   OF   HYGIENE 

Body  and  Mind.  --  The  body  is  a  living  machine, 
and  the  mind  is  the  engineer  that  controls  it.  The 
body  is  useless  without  the  mind,  and  the  mind  can 
do  nothing  except  by  means  of  the  body.  The  two 
must  work  together.  When  either  one  is  out  of  order, 
the  other  also  suffers. 

One  of  the  greatest  of  all  the  differences  between 
a  man  and  a  tree  is  that  a  man  has  a  mind,  and  a 
tree  has  none.  A  tree  grows  in  the  way  in  which  the 
soil,  the  weather,  and  other  trees  compel  it  to  grow. 
But  a  man  can  use  his  mind  to  choose  his  home,  his 
food,  the  air  which  he  breathes,  and  the  work  which  he 
does.  He  can  avoid  those  things  which  will  harm  his 
body,  and  can  do  those  things  which  will  keep  it  strong 
and  sound.  If  the  body  is  in  good  order,  we  say  that  it 
is  healthy. 


10;     ,\.*V         THE    STUDY   OF   HYGIENE 

The  Joy  of  Health  and  Strength.  —  The  mind 
takes  delight  in  directing  the  actions  of  a  sound  body. 
A  healthy  boy  runs  for  the  fun  of  running  fast,  and 
climbs  hills  and  trees  for  the  pleasure  of  using  his 
strength.  He  studies  difficult  lessons  for  the  joy  of 
thinking,  and  puts  his  whole  mind  to  a  puzzle  for  the 
delight  of  solving  it.  He  has  no  pains  or  other  un- 
comfortable feelings,  and  he  performs  all  his  actions 
so  smoothly  and  easily  that  he  almost  forgets  that  he 
has  a  body. 

Most  boys  and  girls  do  not  always  feel  bright  and 
active,  but  sometimes  they  have  aches  and  pains  in 
their  bodies,  and  are  too  weak  to  work  or  play  or 
think.  When  they  feel  like  this,  they  are  either  over- 
tired or  sick. 

Is  Sickness  Necessary  ?  —  Men  used  to  think  that 
sickness  was  necessary.  They  supposed  that  diseases 
were  caused  by  mighty  powers  in  the  air  or  ground, 
just  as  storms  and  earthquakes  were  caused.  They 
thought  that  sickness  could  no  more  be  prevented  than 
rainy  days.  Now  we  know  that  sickness  is  not  often 
caused  by  those  things  which  are  naturally  found  in 
the  air  or  ground.  Most  forms  of  sickness  come  from 
causes  which  may  readily  be  prevented,  such  as  dirt, 
spoiled  food,  foul  air,  and  wrong  eating.  A  school 
child  can  understand  how  the  common  forms  of  sick- 
ness are  caused,  and  how  they  may  be  prevented. 

Progress  in  Health  Matters.  —  In  the  United  States 
there  are  always  over  a  million  persons  who  are  sick. 


THE   STUDY   OF   HYGIENE  n 

About  two  hundred  thousand  doctors  are  occupied  in 
caring  for  them.'  The  expenses  of  the  sickness  and  the 
value  of  the  time  lost  by  the  sick  are  at  least  a  billion 
dollars  a  year.  But  no  one  can  estimate  the  suffering 
and  anxiety  which  are  borne  by  the  sick  and  their 
friends. 

There  is  not  so  much  sickness  among  civilized  nations 
now  as  there  was  in  former  days.  We  know  this  from 
a  study  of  the  records  of  deaths,  and  from  the  history 
of  epidemics. 

1.  The  death  rate  of  a  country  is  the  number  of 
persons  dying  each  year  in  every  thousand  inhabitants. 
The  governments  of  all  civilized  lands  have  long  been 
keeping  records  of  all  persons  who  die  in  those  countries. 
Before  the  year  1800,  about  fifty  or  sixty  persons  died 
each  year  in  every  thousand  inhabitants  of  England, 
Germany,  and  the  United  States.     Now,  only  sixteen  or 
eighteen  persons  die  in  every  thousand  inhabitants. 
But  in  India  the  death  rate  is  now  as  high  as  it  was  in 
England  a  century  ago.     This  is  because  the  people  of 
India  are  as  ignorant  of  health  matters  now  as  the 
people  of  England  were  a  century  ago. 

2.  The  average  age  at  which  persons  die  in  civilized 
lands  is  now  nearly  double  the  average  age  at  which 
they  died  a  century  ago.     The  tombs  and  mummies  of 
ancient  Egypt  show  that  the  Egyptians  died  at  an 
average  age  of  about  twenty-two  years.     In  the  city 
of  Geneva,  Switzerland,  the  average  age  of  persons  dy- 
ing in  the  year  1600  was  twenty-one  years;    in  1700, 


12  THE   STUDY  OF  HYGIENE 

thirty-two  years;  in  1800,  thirty-eight  years.  Now, 
the  average  age  of  those  dying  in  Geneva  is  over  forty- 
five  years.  This  is  about  the  average  age  at  which 
persons  die  in  the  United  States,  England,  and  Ger- 
many. But  in  India  and  Russia  the  average  age  at 
death  is  now  about  twenty-five  years,  or  about  the 
same  as  it  was  in  ancient  Egypt.  The  people  of 
those  countries  which  are  the  most  advanced  in  civi- 
lization and  knowledge  live  about  twice  as  long  as  the 
people  of  the  less  civilized  lands. 

3.  A  disease  which  spreads  through  a  whole  town 
or  country  is  called  an  epidemic  or  pestilence.  The 
people  of  olden  times  were  always  in  fear  of  war  and 
pestilence.  Thousands  of  men  were  killed  each  year 
by  useless  and  cruel  wars,  but  millions  of  men,  women, 
and  children  were  killed  by  diseases  which  are  now 
seldom  seen.  In  England  in  the  fourteenth  century, 
half  of  the  population  died  from  the  plague  in  a  single 
year.  One  hundred  and  two  English  colonists  landed 
at  Plymouth,  Massachusetts,  in  December,  1620,  and 
before  the  next  spring  fifty-two  of  them  had  died  from 
what  is  supposed  to  have  been  typhus  fever.  In  1879 
one  tenth  of  the  inhabitants  of  the  Philippine  Islands 
died  from  cholera.  The  plague,  typhus  fever,  and 
cholera  are  now  almost  unknown  among  civilized 
people,  but  these  diseases  still  go  on  in  India  and  other 
half-civilized  lands.  Now  and  then  a  few  cases  reach 
the  United  States,  but  the  diseases  do  not  spread 
because  great  care  is  taken  to  check  them. 


THE    STUDY   OF   HYGIENE  13 

Cause  of  Epidemics.  -  -  The  great  epidemics  of  olden 
times  were  spread  in  very  simple  ways,  and  could  easily 
have  been  prevented.  The  plague  was  spread  by  rats 
and  fleas  which  swarmed  over  the  thatched  roofs  and 
mud  floors  of  the  huts  of  the  people.  About  the  year 
1900  rats  from  foreign  countries  brought  the  plague  to 
San  Francisco,  but  the  disease  was  stopped  by  making 
the  foundations  and  cellars  of  the  buildings  rat  proof, 
so  that  the  animals  could  not  find  hiding  places. 

Typhus  fever  spreads  among  people  who  are  over- 
crowded. The  colonists  of  Plymouth  were  badly  over- 
crowded both  on  their  ship  and  in  their  houses.  They 
had  no  proper  means  of  bathing  and  no  way  of  separat- 
ing the  sick  from  the  well.  To-day,  there  is  hardly  a 
place  in  the  United  States  where  people  have  to  live  in 
the  way  the  colonists  lived,  and  therefore  typhus  fever 
is  almost  unknown  in  this  country. 

Cholera  is  spread  principally  among  those  who  drink 
impure  water.  In  1832  an  epidemic  of  cholera  broke 
out  in  New  York,  and  all  the  people  who  could  get  away 
from  the  city  left  it  in  terror.  At  that  time  the  drink- 
ing water  was  drawn  from  wells  which  were  dug  along 
the  edges  of  the  streets,  and  the  water  was  foul  from 
slops  and  garbage  which  were  thrown  upon  the  ground. 
The  people  were  made  sick  by  drinking  house  slops  and 
sewage.  In  1840  pure  water  was  brought  to  the  city 
through  the  Croton  aqueduct,  and  since  that  time  the 
people  of  New  York  have  not  been  in  real  danger  of 
cholera. 


I4  THE    STUDY   OF   HYGIENE 

These  examples  are  given  to  show  the  simple  nature 
of  the  causes  of  most  diseases,  and  how  they  are  in  our 
control.  It  is  not  nice  to  have  rats  in  our  houses ;  it 
is  not  fashionable  to  be  dirty ;  and  we  are  ashamed  to 
have  a  bad  odor  about  our  clothes  or  houses.  But  the 
feelings  which  educated  persons  have  about  dirt  and 
bad  odors  are  not  founded  merely  upon  style  and  show. 
Failure  to  keep  rats  and  other  vermin  out  of  our  houses, 
and  failure  to  keep  clean,  would  mean  sickness  and  death 
now,  just  as  in  olden  times.  You  may  prevent  a  great 
deal  of  sickness  by  doing  the  simple  things  which  every 
polite  and  thoughtful  person  in  a  modern  town  is  ex- 
pected to  do. 

Diseases  of  the  Present.  —  Leprosy,  plague,  typhus 
fever,  and  smallpox  were  formerly  extremely  common 
in  all  civilized  lands.  Now,  they  are  seldom  seen. 
Yellow  fever  and  malaria  have  been  wiped  out  of  Pan- 
ama simply  by  exterminating  the  mosquitoes  from  the 
place.  But  a  great  deal  still  remains  to  be  done.  Only 
about  one  third  of  all  deaths  in  the  United  States  are 
due  to  old  age,  and  over  half  are  caused  by  diseases 
which  may  easily  be  prevented.  Typhoid  fever  is 
still  a  common  disease,  and  what  we  call  colds  are  ex- 
tremely common.  Consumption  is  now  so  common 
that  it  is  called  the  great  white  plague,  and  one  tenth  of 
all  deaths  among  white  races  is  due  to  it.  We  think  it 
is  a  terrible  thing  that  one  tenth  of  the  people  of  the 
Philippine  Islands  should  have  died  from  cholera  in 
1879,  and  yet  one  person  in  every  ten  who  now  live  in 


THE   STUDY   OF   HYGIENE  15 

the  United  States  will  die  from  consumption,  unless  a 
great  deal  more  is  done  in  the  near  future  than  in  the 
past  to  prevent  the  disease. 

Helping  Each  Other  to  Keep  Well.  — You  cannot  keep 
well  by  thinking  of  yourself  alone.  You  must  think  of 
the  health  of  others  in  order  to  protect  your  own  health. 
If  you  allow  some  one  to  catch  tonsillitis  from  you,  he 
may  give  the  disease  to  a  third  person,  who  may  give 
the  disease  back  to  you  a  month  or  two  after  you  re- 
cover from  your  first  sickness. 

You  will  often  be  soiled  with  dust  from  streets  over 
which  diseased  persons  and  animals  have  scattered 
the  germs  of  sickness.  You  will  often  breathe  air  which 
the  sick  have  breathed,  and  will  often  buy  food  which 
has  been  handled  by  unhealthy  persons.  What  others 
do  will  affect  your  own  health,  and  what  you  do  will 
affect  the  health  of  other  persons.  You  are  only  one 
among  thousands  of  the  inhabitants  of  a  town,  but  the 
healthfulness  of  your  town  will  depend  on  what  each 
separate  inhabitant  does.  When  you  help  others  to 
keep  well,  you  also  help  yourself  to  be  healthy. 

Teaching  the  Care  of  Health.  —  A  little  child  learns 
a  great  deal  about  the  care  of  his  body  from  his  parents. 
When  he  goes  to  school,  he  learns  more  about  its  care 
from  his  teachers,  and  from  the  books  which  he  studies. 
Later  in  life  he  learns  from  the  advice  of  doctors,  from 
public  lectures,  and  from  articles  in  books,  newspapers, 
and  magazines. 

Public  schools  are  among  the  best  of  all  means  for 


16  THE   STUDY   OF   HYGIENE 

teaching  the  preservation  of  health.  Most  states  now 
have  laws  that  every  public  school  shall  teach  its  pupils 
how  to  take  care  of  their  bodies,  and  how  to  prevent  dis- 
eases. If  all  boys  and  girls  will  learn  to  do  their  part 
in  the  promotion  of  health,  the  next  generation  of  men 
and  women  will  be  a  vigorous,  happy  race.  Colds 
and  consumption  will  be  as  rare  as  leprosy  is  now.  All 
will  live  to  a  ripe  old  age,  and  sickness  and  pain  will 
be  almost  unknown.  No  one  will  feel  that  life  is  a  bur- 
den, but  all  will  feel  the  joy  that  comes  from  health 
and  strength  (p.  10). 

Hygiene.  — The  study  of  keeping  the  body  in  good 
health  is  called  hygiene.  In  it  you  will  study  such 
subjects  as  bathing,  eating,  drinking,  clothing,  breath- 
ing, exercise,  and  sleep. 

Hygiene  also  includes  the  study  of  the  methods  and 
conditions  by  which  diseases  are  prevented.  It  there- 
fore treats  of  such  subjects  as  the  purity  of  food,  the 
wholesomeness  of  drinking  water,  the  freshness  of  the 
air,  and  the  disposal  of  sewage. 

Anatomy  and  Physiology.  —  Before  you  can  under- 
stand the  care  of  the  body,  you  must  know  something 
about  the  structure  of  its  living  machinery,  and  how  it 
does  its  work.  The  study  of  the  structure  of  the  body 
is  called  anatomy,  and  the  study  of  its  work  and  action 
is  called  physiology.  You  must  study  the  anatomy  and 
physiology  of  each  part  of  the  body  in  order  to  under- 
stand the  care  of  that  part. 


THE   STUDY  OF   HYGIENE  17 

QUESTIONS 

What  are  some  of  the  signs  of  good  health  ? 

What  are  some  of  the  signs  of  poor  health  ? 

What  effect  does  sickness  of  the  body  have  upon  the  mind  ? 

About  how  many  persons  in  the  United  States  are  sick  at  one 
time? 

About  how  much  money  does  sickness  cost  the  people  of  the 
United  States  each  year  ? 

Give  some  reasons  for  thinking  that  there  is  less  sickness  now 
than  formerly. 

What  is  the  average  death  rate  in  the  United  States  ? 

What  is  the  average  length  of  life  in  the  United  States  ? 

What  is  an  epidemic  ? 

Name  some  epidemics  which  used  to  be  common,  but  are  now 
seldom  seen. 

What  are  some  of  the  reasons  why  deadly  epidemics  no  longer 
occur  ? 

Name  some  deadly  diseases  which  are  now  common. 

How  does  a  person  protect  his  own  health  when  he  helps 
others  to  keep  well  ? 

What  is  hygiene  ? 

What  is  physiology  ? 

What  is  anatomy  ? 

What  is  the  object  of  teaching  hygiene  in  schools  ? 


GEN.    HYG.  —  2 


CHAPTER  II 

ORGANS   AND   CELLS 

Life  and  Growth.  —  The  food  upon  which  the  body 
lives  has  no  life,  but  it  becomes  living  blood,  flesh,  and 
bone  in  the  body.  After  remaining  alive  for  a  few 
days  or  weeks,  the  living  flesh  becomes  worn  out  and  is 
changed  back  to  dead  and  lifeless  forms,  and  new  flesh 
is  formed  to  take  its  place. 

The  constant  building  up  of  worn-out  parts  of  the 
body  is  what  is  called  life  and  growth.  Lifeless  things 
change  and  go  to  pieces,  and  cannot  build  themselves 
up  again.  Living  things  are  said  to  be  alive  because 
they  build  themselves  up  as  fast  as  they  wear  out. 

Voluntary  and  Involuntary  Actions.  —  A  person  can 
use  his  mind  in  thinking,  and  his  body  in  moving,  when- 
ever he  wishes  to  do  so.  These  two  kinds  of  work  are 
directed  by  the  mind,  and  are  called  voluntary  actions. 

The  actions  of  growth  and  repair  are  only  slightly 
under  the  control  of  the  mind,  and  are  called  involuntary 
actions.  These  actions  go  on  while  a  person  is  asleep 
even  better  than  they  do  while  he  is  awake.  The  same 
kinds  of  action  go  on  in  a  tree,  which  has  no  mind  at  all. 

Division  of  Labor  in  the  Body.  —  Each  action  takes 
place  in  a  particular  part  of  the  body,  and  in  no  other 

18 


ORGANS   AND    CELLS 


Brain 


Spinal  cord 


part.  One  part  of  the  body  thinks,  another  prepares 
food,  another  supplies  air  to  all  the  rest  of  the  body, 
and  other  parts  get  rid  of  the  worn-out  flesh.  A  part  of 
the  body  which  has  a  particular  work  to  do  is  called 
an  organ. 

Organs  of  Digestion.  —  The  act  of  changing  food  to 
forms  which  living  flesh  can  use  is  called  digestion. 
There  are  four  principal 
organs  of  digestion:  i,  a 
bag,  called  the  stomach, 
which  receives  the  food 
when  it  is  swallowed ;  2,  a 
long  tube,  called  the  intes- 
tine, in  which  the  food  is 
dissolved ;  3,  a  mass  of 
flesh,  called  the  pancreas, 
in  which  a  liquid  is  pre- 
pared for  dissolving  the 
food ;  and  4,  a  large  mass 
of  flesh,  called  the  liver,  in 
which  the  food  is  made  a 
part  of  the  blood. 

Organs  of  Circulation. 
-  Blood  carries  digested 
food  through  all  parts  of 
the  body,  and  its  flow 
is  called  the  circulation. 
There  are  two  principal 
organs  of  circulation:  i,  a 


Heart 
Diaphragm 


Intestine 


Diagram  of  the  position  of  the  prin- 
cipal organs  of  the  body. 


20  ORGANS  AND   CELLS 

pump,  called  the  heart,  which  keeps  the  blood  in 
motion;  and  2,  a  vast  number  of  tubes,  which  con- 
duct the  blood  through  all  the  flesh  and  bones. 

Organs  of  Respiration.  -  -  The  body  cannot  work, 
or  even  live,  unless  a  constant  supply  of  air  reaches  every 
part.  Taking  air  into  the  body,  and  the  changes  pro- 
duced by  the  air,  are  called  respiration.  The  principal 
organs  of  respiration  are  the  lungs. 

Organs  of  Excretion.  —  Getting  rid  of  worn-out 
substances  is  called  excretion.  There  are  two  principal 
organs  of  excretion:  the  kidneys  and  the  skin.  The 
lungs,  the  liver,  and  the  intestine  are  also  important 
organs  of  excretion. 

Organs  of  the  Nervous  System.  —  All  the  parts  of  the 
body  are  made  to  help  one  another,  and  to  work  to- 
gether, by  means  of  the  nervous  system.  There  are 
three  principal  organs  of  the  nervous  system:  i,  the 
brain,  situated  in  the  top  of  the  head ;  2,  the  spinal 
cord,  situated  in  the  backbone ;  and  3,  long  strings  of 
flesh,  called  nerves,  which  extend  from  the  brain  and 
spinal  cord  to  all  parts  of  the  body. 

Organs  for  Voluntary  Work.  —  There  are  two  organs 
for  doing  voluntary  work:  i,  the  brain,  which  does  the 
work  of  thinking ;  2,  a  large  number  of  bundles  of  lean 
meat,  called  muscles,  which  produce  motions.  Stiff 
rods  and  plates,  called  bones,  support  the  soft  flesh  and 
assist  the  muscles  to  produce  nearly  all  the  voluntary 
movement  of  the  body. 

Cells.  —  An  organ  is  not  like  a  lump  of  clay  which  is 


ORGANS  AND   CELLS 


the  same  throughout  its 
whole  mass,  but  it  is  made 
up  of  microscopic  living 
things  called  cells.  All  flesh 
is  composed  of  cells  which 
do  their  work  like  separate 
animals. 

Cells  in  Lower  Animals 
and  Plants.  —  All  animals 
and  plants  are  composed  of 
cells.  In  the  •  lowest  forms 
of  living  beings  each  animal 

and   plant    is    composed  of    a      Slipper  animalcules.    Magnified. 

single  cell.  A  common  one-celled  animal  is  called  the 
slipper  animalcule,  or  paramecium.  It  is  microscopic 
in  size,  and  is  found  in  stagnant 
water. 

Place  a  handful  of  hay  or  dry 
grass  in  a  jar  of  water,  and  leave 
the  jar  in  a  warm  room.  After 
two  or  three  weeks  the  water  will 
usually  contain  great  numbers  of 
tiny  white  specks,  each  of  which 
is  a  paramecium.  If  you  look  at 
a  drop  of  the  water  with  a  micro- 
scope, you  can  see  the  shape  and 
structure  of  the  animals  as  they 
move  rapidly  through  the  water. 
Collect  some  of  the  green,  silky 


Threads  of  pond  algae. 


22 


ORGANS  AND   CELLS 


threads  which  float  on  still  ponds,  or  grow  on  sticks 
and  stones  in  the  water.  These  threads  are  green 
plants  called  alga.  Examine  a  few  of  the  plants 
under  a  microscope.  Each  plant  is  a  thread  which 
consists  of  a  single  row  of  oblong  cells  joined  end  to 
end. 

All  higher  plants  and  animals,  such  as  wheat  or  a 
bird,  consist  of  masses  of  cells. 

Size  and  Shape  of  Cells.  —  The  different  kinds  of 
cells  in  the  human  body  vary  in  size  and  shape,  but  not 

one  of  them  is  large  enough 

AUk  to  kg  seen  with  the  naked 

W      eye.     If  you  scrape  the  skin 

m  &m   ^  with  a  knife,  you  will  get  a 

white    powder    which    looks 

•     <CTT  like  fl°ur-    This  powder  con- 

JjMNfe  s^sts  °f  ce^s  fr°m  the  outer 

covering  of  the  skin.     If  you 

•JP       m^%  1°°^   at   ^e   Powder  with  a 

microscope,  the  separate  cells 
appear  like  flat  scales.  The 
largest  of  these  cells  measure 
about  one  five-hundredth  of 
an  inch  across. 

A  muscle  cell  is  shaped  like  a  string,  and  is  about 
one  five-hundredth  of  an  inch  in  diameter  and  about  one 
fiftieth  of  an  inch  in  length.  A  blood  cell  is  round  and 
almost  flat,  and  measures  about  one  three-thousandth 
of  an  inch  across.  If  you  put  a  bit  of  flesh  under  a  micro- 


Cells  scraped  from  the  back  of 
the  hand.     Magnified. 


ORGANS   AND    CELLS 


23 


Cells  of  epithelium  from  the 
mouth. 


scope,  you  can  tell  from  what  organ  it  came  by  noticing 
the  size,  shape,  and  arrangement  of  its  cells. 

How  Cells  Grow.  —  Most  of 
the  cells  of  a  baby's  body  are 
of  the  same  size  and  shape  as 
the  cells  of  a  grown  man,  but 
there  are  not  so  many  of  them. 
A  child  does  not  grow  by  mak- 
ing the  cells  of  its  body  larger, 
but  by  making  their  number 
greater. 

A  cell  consists  of  two  parts: 
i,  a  soft  jellylike  substance,  which  forms  the  greater 
part  of  the  cell ;  and  2,  a  darker  bit 
of  matter,  called  the  nucleus,  which 
is  situated  near  the  center  of  the  cell. 
When  a  cell  reaches  full  size,  its  nu- 
cleus divides  into  two  parts,  and  the 
rest  of  the  cell  then  splits  itself  in 
half  between  the  halves  of  the  nu- 
cleus. Thus  a  young  cell  is  just  half 
the  size  of  a  full-grown  cell,  but  it  is 
like  a  full-grown  cell  in  all  other  re- 
spects. 

Connective  Tissue.  —  A  group  of 
cells  which  look  and  act  alike  is 
called  a  tissue.  The  working  cells  of 
every  organ  are  held  in  place  by  a  tissue  called  con- 
nective tissue.  These  cells  are  small,  and  have  long, 


Connective  tissue 
around  muscle 
cells.  Magnified. 


24 


ORGANS  AND   CELLS 


slender  arms  which  are  tough  and  strong.     These  arms 
extend  around  and  between  the  cells,  and  hold  them  in 

place.  If  you  examine  the 
end  of  a  piece  of  beefsteak, 
you  will  find  a  white  net- 
work of  tough  connective 
tissue  lying  between  red 
bundles  of  soft  muscle  cells. 
Some  connective  tissue  is 
found  in  every  part  of  the 
body.  It  forms  the  greater 
part  of  the  skin. 

Epithelial  Tissue.  —  The 
whole  skin  is  covered  with 
cells  which  are  like  soft 
scales.  These  cells  are  called 
epithelial  tissue,  or  epithe- 
lium. One  of  their  principal  uses  is  to  protect  the 
soft  and  delicate  flesh  under  them. 

Glands. --The  skin  is  always  moist  with  a  liquid, 
called  the  sweat,  or  perspiration.  The  sweat  comes 
from  pores,  which  are  the  openings  of  deep,  narrow  tubes 
extending  into  the  skin.  Each  tube  is  lined  with  cells 
of  epithelium,  which  extend  down  the  tube  from  the 
surface  of  the  skin.  The  use  of  the  cells  of  epithelium 
in  the  tube  is  to  form  the  sweat  or  perspiration  out  of 
material  brought  to  them  by  the  blood. 

A  tube  composed  of  cells  of  epithelium,  which  form 
a  substance  out  of  the  blood,  is  called  a  gland.  The 


Beefsteak.        Connective     tissue 
around  bundles  of  muscle  cells. 


ORGANS  AND    CELLS  25 

substance  which  a  gland  forms  is  called  a  secretion. 
Sweat  glands  are  found  in  the  skin  on  nearly  every  part 
of  the  body. 

The  kidneys,  liver,  and 
pancreas  are  glands.  They 
are  composed  of  tubes  of  epi- 
thelium which  either  manu- 
facture substances  for  the 
use  of  the  body,  or  take 
waste  substances  from  the 
blood. 

The  stomach  and  intestine 
contain  glands  which  secrete 
digestive  juices. 

Mucous  Membrane.  —  A 
loose  sheet  of  tissue,  which 
is  like  thin,  soft  skin,  lines 

the    inside    of    the    nose    and  Glands  of  the  intestine. 

mouth.  It  also  extends  down  the  tubes  which  sup- 
ply air  and  food  to  the  body,  and  forms  a  kind  of 
inner  skin  in  the  lungs,  the  stomach,  and  the  intestine. 
This  inner  skin  is  called  mucous  membrane.  It  is 
covered  with  epithelial  cells,  which  are  like  those  on 
the  surface  of  the  skin. 

Mucous  membrane  contains  glands  which  are 
similar  to  those  on  the  skin.  These  glands  secrete 
a  slippery  liquid,  called  mucus.  One  of  the  princi- 
pal uses  of  mucus  is  to  protect  the  mucous  mem- 
brane. 


26  ORGANS  AND   CELLS 

Nature  of  the  Processes  of  Life.  —  Men  used  to 
think  that  the  processes  of  life  were  carried  on  by  what 
they  called  vital  spirits,  and  that  sickness  was  caused 
by  evil  spirits  which  made  their  home  in  the  sick  per- 
son's body  for  a  time.  Now  it  is  known  that  the  work 
which  goes  on  in  most  parts  of  the  body  is  done  by  the 
same  means  and  in  the  same  manner  that  work  is  done 
in  a  workshop  or  laboratory.  For  example,  the  heat  of 
the  body  may  be  measured  in  the  same  way  as  the  heat 
of  a  bottle  of  water.  Food  may  be  digested  in  a  bottle 
in  the  same  way  that  it  is  digested  in  the  stomach. 

There  are  exact  means  of  knowing  the  changes  which 
take  place  in  the  body,  both  in  health  and  in  disease. 
The  study  of  physiology  has  led  to  the  discovery  of 
the  causes  of  most  forms  of  sickness  and  of  the  means  of 
keeping  the  body  healthy.  You  can  learn  the  proper 
care  of  your  body  as  readily  as  you  can  learn  to  care 
for  an  automobile. 

QUESTIONS 

Name  one  great  difference  between  bodies  which  are  living 
and  those  which  are  lifeless. 

Name  the  two  principal  voluntary  actions  which  take  place 
in  the  body. 

Name  some  involuntary  actions  which  take  place  in  the 
body. 

What  is  an  organ  ? 

Name  the  principal  organs  of  digestion ;  of  circulation ;  of 
excretion;  of  the  nervous  system;  of  voluntary  work;  of 
respiration. 


ORGANS   AND   CELLS  27 

What  are  cells  ? 
What  is  the  size  of  cells  ? 
How  do  cells  multiply  in  number  ? 
Describe  an  animal  which  consists  of  a  single  cell. 
Describe  a  plant  in  which  cells  may  be  readily  seen. 
What  is  a  tissue  ? 
What  is  connective  tissue  ? 
What  is  epithelial  tissue  ? 
What  is  mucous  membrane  ? 
Describe  a  gland. 
What  is  a  secretion  ? 
Name  some  glands. 

Name  some  living  processes  which  may  be  measured  and 
imitated  in  a  laboratory. 


CHAPTER  III 
COMPOSITION  OF  THE  BODY 

The  Substances  in  the  Body.  -  -  The  substances  of 
which  the  body  is  composed  are  constantly  changing. 
Over  a  pound  of  flesh  wears  away  each  day,  and  new 
flesh  is  formed  in  its  place. 

The  body  is  composed  of  five  different  kinds  of  sub- 
stances. Their  names  are  water,  minerals,  protein, 
fat,  and  sugar.  It  is  important  for  you  to  remember 
these  five  substances  and  to  understand  what  they  are, 
for  every  act  of  the  body  produces  a  change  in  them. 

Water.  —  Water  is  the  most  abundant  substance  in 
the  body.  Three  fourths  of  the  weight  of  the  flesh, 
and  one  fifth  of  the  weight  of  bone,  is  water.  It  does 
not  exist  pure  and  alone  by  itself  in  any  part  of  the  body, 
but  it  is  always  found  mixed  with  other  substances.  It 
does  not  change  the  composition  of  the  other  substances 
of  the  body,  but  it  softens  and  dissolves  them  so  that 
the  processes  of  life  can  go  on. 

Minerals.  —  If  a  person's  body  were  burned,  about 
one  twelfth  of  it  would  be  left  as  ashes.  The  ashes  are 
mineral  substances  which  are  mixed  with  the  flesh, 
blood,  and  bone  of  every  part  of  the  body.  The  most 

28 


COMPOSITION   OF   THE   BODY  29 

abundant  of  the  minerals  is  lime.  Most  of  the  lime  is 
found  in  the  bones,  but  some  is  also  found  in  flesh  and 
blood.  Salt,  soda,  potash,  and  iron  are  other  important 
minerals  which  are  always  found  in  the  body. 

Protein.  —  Protein  is  a  substance  which  may  be 
found  in  every  living  thing.  An  older  name  for  it  is 
albumin.  It  is  formed  only  by  living  beings.  All  life 
is  carried  on  by  means  of  it,  and  without  it  there  can 
be  no  life.  Growing  cells  consist  principally  of  protein 
and  water,  with  a  little  mineral  matter.  The  protein 
in  the  body  weighs  about  one  eighth  as  much  as  the 
whole  body. 

Pure  protein  is  a  solid  substance  which  is  like  the 
dried  white  of  an  egg.  It  does  not  exist  alone  and  in 
a  pure  form  in  any  part  of  the  body,  but  it  is  always 
found  dissolved  in  water  and  mixed  with  a  little  mineral 
matter.  When  we  speak  of  the  protein  of  the  body  we 
mean  a  liquid  or  jellylike  mixture  of  protein,  water, 
and  minerals. 

The  liquid  protein  of  flesh  becomes  changed  to  a  solid 
form  when  it  is  heated.  This  change  from  a  liquid  to 
a  solid  form  is  called  coagulation.  Examples  of  the 
coagulation  of  protein  are  the  hardening  of  the  white 
of  an  egg  when  it  is  boiled,  the  curdling  of  milk  when  it 
sours,  and  the  clotting  of  blood  after  it  flows  from  the 
body. 

Fat.  —  About  one  tenth  of  the  body  consists  of  fat 
which  is  like  lard  or  tallow.  Collections  of  fat  lie  under 
the  skin,  and  between  the  bundles  of  muscles,  and 


COMPOSITION   OF   THE   BODY 


around  the  organs  of  the  body.     Fat  itself  is  not  a 
living  substance,  but  what  is- called  fat  meat  consists 

of  tiny  pockets  of  living 
connective  tissue  cells  filled 
with  fat.  The  fat  of  a  liv- 
ing body  is  not  solid  as  it 
is  in  cold  meat,  but  during 
life  the  heat  of  the  body 
keeps  it  in  a  liquid  form. 

The  use  of  fat  is  to  keep 
the  body  warm,  and  to  fur- 
nish it  with  strength  to 
work.  When  a  person  can- 
not eat  food,  the  body  uses 
up  its  own  fat  as  food.  It 
then  loses  weight  and  be- 
comes thin.  Fat  is  food  stored  up  to  be  used  when  the 
body  cannot  get  other  food. 

Sugar.  —  About  eight  ounces  of  substances  which 
are  like  sugar  are  found  in  the  liver  and  muscles.  Their 
use  is  to  supply  the  body  with  heat  and  strength. 

Food.  —  The  water,  minerals,  protein,  fat,  and  sugar 
of  the  body  come  from  the  food  which  is  eaten.  All 
food  consists  of  these  same  kinds  of  substances.  The 
body  takes  about  five  or  six  pounds  of  them  daily,  and 
it  must  give  them  off  in  nearly  the  same  amounts,  for 
its  weight  changes  very  slowly.  But  before  getting  rid 
of  them,  the  body  changes  some  of  them  by  a  process, 
called  oxidation,  which  is  like  the  burning  in  a  fire. 


Fat  tissue. 


COMPOSITION   OF    THE   BODY 


Oxygen.  —  No  person  can  live  unless  he  takes  air 
into  his  body  several  times  each  minute.  The  part  of 
the  air  which  the  body  uses  is  called  oxygen.  This 
substance  forms  about  one  fifth  of  the  whole  air.  The 
quantity  of  oxygen  which  the  body  takes  from  the  air 
each  day  weighs  about  twice  as  much  as  all  its  food 
except  water.  The  oxygen  passes  through  the  body 
with  the  blood,  and  joins  itself  to  food  and  flesh.  The 
process  of  joining  oxygen  to  another  substance  is  called 
oxidation. 

Oxidation  in  a  Fire.  —  A  fire  is  an  example  of  oxida- 
tion. Burning  is  the  process  of  uniting  oxygen  with 
fuel,  such  as  wood, 
coal,  or  oil.  When 
wood  burns,  more  than 
its  own  weight  of  oxy- 
gen unites  with  it 
quickly  and  forcibly. 
While  the  two  sub- 
stances are  uniting, 
they  produce  a  great 
deal  of  heat.  When 


oxroE 


Diagram  of  oxidation  in  a  stove. 


the  oxygen  and  the  wood  are  joined  together,  they  be- 
come smoke  and  ashes. 

Heat  from  Oxidation.  —  Oxidation  in  the  body  is  the 
same  kind  of  .process  as  that  which  takes  place  when 
wood  burns  in  a  stove,  but  it  takes  place  slowly  and 
gently  in  the  body.  It  produces  the  same  quantity 
of  heat  that  burning  the  food  or  flesh  in  a  stove  would 


32  COMPOSITION   OF   THE   BODY 

have  produced.  The  heat  produced  by  oxidation  keeps 
the  body  warm. 

Power  from  Oxidation.  —  Oxidation  also  gives  the 
body  power  and  strength  to  do  work,  just  as  the  burn- 
ing of  wood  and  coal  supplies  power  to  a  steam  engine. 
All  the  strength  of  the  body  to  walk,  or  speak,  or  think, 
or  to  do  anything  else,  comes  from  oxidation.  When 
we  say  that  the  body  wears  itself  out  by  working,  we 
mean  that  it  oxidizes  its  flesh  and  food,  just  as  a  loco- 
motive engine  burns  up  coal  when  it  runs. 

Worn-out  Flesh.  -  -  The  worn-out  substances  and 
waste  matters  of  the  body  are  mostly  food  and  flesh 
which  have  been  oxidized.  They  are  composed  of  the 
same  kinds  of  substances  that  are  in  the  smoke  and 
ashes  of  a  fire. 

The  protein,  fat,  and  sugar  of  food  and  flesh  are  com- 
posed of  nearly  the  same  kind  of  substances  of  which 
wood  and  coal  are  composed.  The  names  of  the  two 
most  abundant  of  these  substances  are  carbon  and  hydro- 
gen. The  oxidation  of  these  two  substances  supplies 
most  of  the  heat  and  power  of  the  body. 

Carbon  Dioxide.  —  Carbon  is  usually  a  solid.  A 
common  form  of  it  is  charcoal.  When  oxygen  unites 
with  it,  the  two  substances  become  a  gas  called  carbon 
dioxide.  This  is  the  same  gas  that  is  put  into  soda 
water  to  make  it  bubble  and  foam.  Carbon  dioxide 
is  produced  in  fires  by  the  oxidation  of  the  carbon  of 
the  fuel,  and  is  found  in  the  smoke.  It  is  also  produced 
by  the  oxidation  of  the  carbon  in  flesh  and  food. 


COMPOSITION   OF   THE  BODY  33 

If  you  put  one  end  of  a  tube  into  a  glass  of  clear  lime- 
water  and  blow  through  the  other  end,  the  carbon 
dioxide  from  your  breath  will  turn  the  limewater  milky. 
This  is  a  test  by  which  the  presence  of  carbon  dioxide 
may  be  known. 

Manufacture  of  Water  in  the  Body.  —  Free  hydrogen 
is  a  gas,  and  is  one  of  the  principal  substances  in  the  gas 
which  is  burned  in  houses.  It  is  also  abundant  in  wood, 
coal,  and  oil,  and  in  a  person's  flesh  and  food.  When 
oxygen  unites  with  hydrogen,  the  two  gases  become 
water.  When  a  cold  lamp  chimney  is  put  upon  a  lighted 
lamp,  the  vapor  of  water  which  is  formed  by  the  burn- 
ing hydrogen  of  the  oil  may  be  seen  on  the  inside  of 
the  chimney.  Nearly  a  pint  of  water  is  formed  each 
day  in  the  body  by  the  oxidation  of  the  hydrogen  of 
food  and  flesh. 

Other  Waste  Matters  of  Oxidation.  —  When  food 
and  flesh  are  oxidized,  the  minerals  are  left  behind  like 
the  ashes  of  a  fire.  The  oxidation  also  leaves  a  small 
quantity  of  partly  burned  substances  which  are  poison- 
ous to  the  body.  Among  them  are  two  substances 
called  urea  and  uric  acid.  These  two  substances  are 
formed  during  the  oxidation  of  protein. 

If  the  oxidation  in  the  body  is  disturbed  in  any  way, 
as  by  improper  eating  or  breathing,  the  waste  substances 
will  be  far  more  poisonous  than  the  carbon  dioxide,  urea, 
and  uric  acid  which  are  naturally  formed.  These  poi- 
sonous waste  substances  are  the  cause  of  much  of  the 
pain  and  weakness  during  most  forms  of  sickness. 

GEN.   HYG. — 3 


34  COMPOSITION  OF   THE  BODY 

QUESTIONS 

Of  what  five  substances  is  the  body  composed  ? 

How  much  of  the  body  is  water  ? 

Of  what  are  the  ashes  of  burned  flesh  composed  ? 

How  much  of  the  body  is  mineral  matter  ? 

Describe  protein.     Give  an  example  of  protein. 

How  much  of  the  body  is  composed  of  fat  ? 

How  is  fat  stored  in  the  body  ? 

How  much  sugar  is  found  in  the  body  ? 

What  is  oxygen  ? 

What  is  oxidation? 

Describe  the  process  of  burning  in  a  fire. 

Compare  oxidation  in  the  body  with  a  fire. 

Of  what  use  is  oxidation  in  the  body  ? 

Of  what  does  worn-out  flesh  in  the  body  consist  ? 

What  is  carbon? 

What  substance  is  produced  when  carbpn  is  oxidized  in  the 
body? 

What  is  hydrogen  ? 

What  substance  is  produced  by  the  oxidation  of  hydrogen  in 
the  body  ? 

What  substances  are  formed  by  the  oxidation  of  protein  ? 


CHAPTER  IV 
BACTERIA 

Infectious  Diseases.  —  Diseases  and  disorders  of  the 
body  may  be  divided  into  two  classes.  First,  there 
are  those  forms  of  sickness  which  arise  from  within 
a  person  himself.  For  example,  weakness  and  sick- 
ness may  be  caused  by  wrong  eating  or  drinking,  or  by 
overwork,  or  by  a  sad  or  worried  mind,  or  by  lack  of 
exercise. 

Second,  sickness  may  be  caused  by  something  which 
enters  a  person's  body  and  grows  there.  All  diseases 
which  are  caught  belong  to  this  class,  and  are  called 
infectious  diseases.  They  are  caused  by  living  plants 
or  animals  called  disease  germs.  The  germs  enter  the 
body,  and  there  multiply  and  grow.  More  than  half 
of  the  deaths  which  occur  before  old  age  are  due  to 
infectious  diseases.  Nearly  all  fevers,  and  what  are 
called  colds,  are  caused  by  disease  germs. 

Bacteria.  —  Germs  of  disease  are  the  smallest  living 
things  that  are  known.  Most  of  them  are  plants,  and 
belong  to  a  group  called  bacteria,  or  microbes,  just  as  an 
oak  belongs  to  a  group  called  trees,  and  wheat  belongs 
to  a  group  called  grass.  Each  bacterium  is  a  single 
cell  which  is  smaller  than  any  cell  of  a  human  body. 
It  is  not  divided  into  distinct  parts,  such  as  roots, 

35 


36  BACTERIA 

branches,  and  fruit,  except  that  on  a  few  kinds  tiny 
projections,  like  hairs,  may  be  seen.  The  separate 
bacteria  cannot  be  seen  without  a  powerful  microscope, 
and  then  they  seldom  appear  larger  than  the  tiny  dots 
and  dashes  of  a  printed  page. 

How  to  see  Bacteria.  —  An  easy  way  to  find  bacteria 
is  to  soak  a  handful  of  hay  in  a  bottle  of  water.  After 

a  few  days  examine  a 
AW-  *  k      *  '   *> ,.-;..         Hil    drop  of  the  water  with 

*     *         ••  * 

a  microscope,  using  its 
greatest  magnifying 
power.  You  will  see 
great  numbers  of  bac- 
teria  that  appear  like 

Bacteria  in  hay  water.  faint    dots   and    dashes 

in  constant  motion. 

How  Bacteria  Grow.  --  Bacteria  increase  in  number 
by  the  simple  process  of  each  one  dividing  itself  into 
two  bacteria,  just  as  if  it  had  been  broken  in  two. 
Each  of  the  two  is  as  complete  and  separate  a  bacterium 
as  the  single  plant  was  before  it  became  divided. 
Within  an  hour  each  of  the  two  may  reach  its  full 
size  and  may  itself  divide  into  two,  thus  making  four 
bacteria.  Each  of  the  four  may  divide  within  another 
hour,  making  eight.  If  this  goes  on  for  twenty-four 
hours,  there  will  be  sixteen  millions  of  bacteria  in  place 
of  only  one,  and  yet  they  are  so  small  that  the  whole 
of  them  would  form  a  lump  no  larger  than  a  small  grain 
of  sand.  At  the  end  of  two  days  the  bacteria  would 


BACTERIA  37 

multiply  to  two  hundred  and  fifty-six  millions  of  mil- 
lions, and  would'  fill  a  pint  measure.  At  the  end  of 
three  days  there  would  be  enough  bacteria  to  load  an 
ocean  steamship.  Bacteria  often  multiply  at  this  rate 
.for  a  few  hours,  but  they  soon  use  up  all  the  food  which 
they  can  reach,  and  their  further  growth  is  then  im- 
possible. 

Where  Bacteria  are  Found.  —  Since  bacteria  multiply 
with  great  rapidity,  they  are  the  most  abundant  of 
all  living  things.  Countless  millions  are  found  in  all 
kinds  of  decaying  substances,  and  in  the  soil.  Water 
usually  contains  a  few  of  them,  and  every  object  is 
sprinkled  with  them.  About  a  thousand  bacteria  are 
found  in  each  drop  of  milk  when  it  is  fresh  and  clean, 
but  over  a  million  are  found  in  each  drop  after  it  has 
stood  for  a  day  in  an  ordinary  pantry. 

Bacteria  are  the  hardest  to  kill  of  all  living  things. 
Drying  or  freezing  does  not  kill  most  of  them,  but  only 
stops  their  growth  until  they  become  wet  or  warm 
again.  When  dried,  they  are  often  blown  away  by  the 
wind,  and  so  bacteria  are  found  in  most  dust,  and  on 
everything  on  which  dust  falls. 

Decay.  —  One  of  the  most  common  effects  caused 
by  bacteria  is  to  destroy  substances  in  which  they  grew. 
A  living  thing  preserves  itself,  but  after  it  dies,  it  usually 
becomes  soft  and  finally  goes  to  pieces,  unless  great 
pains  are  taken  to  preserve  it.  This  natural  process  of 
destruction  is  called  decay,  or  rotting,  and  is  caused  prin- 
cipally by  bacteria. 


BACTERIA 


The  final  result  of  decay  is  to  oxidize  dead  matter, 
and  to  form  the  same  substances  that  would  have  been 
formed  if  the  decaying  matter  had  been  burned.  When 
the  process  of  decay  is  complete,  the  oxidized  products 
are  in  such  a  form  that  plants  can  use  them  as  food, 
and  can  build  the  particles  again  into  living  forms. 
The  fertilizers  which  farmers  spread  upon  their  land 
consist  principally  of  decaying  substances. 

Decay  is  as  necessary  as  growth,  for  if  dead  animals 
and  plants  did  not  decay,  their  remains  would  soon 
cover  the  whole  earth.  Everything  that  is  alive  will 
finally  die,  and  its  particles  will  return  to  the  earth,  air, 
and  water.  The  greater  part  of  the  work  of  destroy- 
ing lifeless  substances  that  were  once  alive  is  done  by 
bacteria. 

Molds.  —  Molds  form  a  class  of  plants  which  grow 
and  act  much  like  bacteria.  The  green  furry  coating 

on  old  bread  or 
cheese  is  mold,  but 
the  fur  on  their 
surface  is  only  the 
fruit  of  the  mold 
plants.  The 
greater  part  of  a 
mold  plant  con- 
sists of  threads 

Mold.     Fruit  stalks  and  spore  cases.  which       grow      be- 

neath   the    surface    of    the    food,    and    are    so    small 
that  they  may  scarcely  be  seen  with  the  naked  eye. 


BACTERIA 


39 


Under  the  microscope,  the  threads  appear  like  long  cells 
joined  end  to  end  into  strings.  Molds  multiply  like 
bacteria,  and  cause  decay  in  substances  in  which  they 
grow,  just  as  bacteria  do. 

Mold  Spores.  —  Many  kinds  of  full-grown  mold 
plants  send  up  tiny  stalks,  each  bearing  a  knob  on  its 
top.  The  knobs  are  hollow  cases  filled  with  tiny  balls 
called  spores. 
Each  spore  is  a 
kind  of  seed  which 
may  grow  and  pro- 
duce a  mold  plant. 

Mold  spores 
float  away  in  the 
air,  and  grow  on 
substances  on 
which  they  fall. 
They  are  scattered 
everywhere,  and  so 
molds  are  found  wherever  there  is  a  soil  to  furnish 
them  with  food  for  growth.  Molds  have  an  important 
effect  on  the  health  of  persons,  for  they  cause  food  and 
other  substances  to  spoil  and  decay,  and  wherever  they 
grow,  bacteria  also  are  likely  to  be  found. 

Canning  Food.  —  A  substance  will  not  decay  if 
there  are  no  living  bacteria  or  molds  in  it.  We  keep 
food  from  decaying  by  boiling  it,  so  as  to  kill  all  living 
bacteria  and  molds  in  it.  We  then  seal  it  in  air-tight 
cans  so  that  no  more  living  germs  will  enter  it.  Food 


Mold  threads. 


40  BACTERIA 

canned  or  preserved  in  this  way  will  remain  fresh  for 
months  or  years. 

Canned  food  often  spoils  because  those  who  put  it  up 
do  not  boil  the  jars  and  their  covers  in  order  to  kill  the 
germs  on  them.  A  good  way  to  can  fruit  is  to  put  it 
into  the  jars  and  put  the  covers  on  loosely.  Then  boil 
the  jars  and  fruit  together,  and  fasten  the  covers  on 
tightly. 

Useful  Bacteria.  —  Many  kinds  of  bacteria  produce 
substances  which  are  pleasant  to  the  taste  or  smell, 
or  which  are  useful  to  man.  Bacteria  change  cider  to 
vinegar.  They  are  necessary  in  making  butter,  for 
butter  made  from  milk  and  cream  which  contains  no 
bacteria  tastes  about  like  lard.  Farmers  depend  on 
bacteria  to  cause  substances  to  decay  and  enrich  the 
soil,  and  cities  often  depend  on  bacteria  of  decay  to 
destroy  their  sewage.  Over  a  thousand  kinds  of  bac- 
teria are  known,  and  nearly  all  of  them  are  useful  to 
man. 

Ptomaines. — In  most  decaying  matter,  substances 
called  ptomaines  (to'ma-ins)  are  formed.  Many  of  the 
ptomaines  are  extremely  poisonous  when  they  are  taken 
into  the  body.  Food  that  is  sour  or  spoiled  often  con- 
tains ptomaines  which  are  likely  to  cause  sickness  in 
any  one  who  eats  the  food.  Spoiled  food  may  usually 
be  known  by  its  unpleasant  smell  and  taste,  but  some 
of  the  most  dangerous  of  all  the  ptomaines  have  neither 
taste  nor  odor,  and  -persons  have  been  poisoned  to 
death  by  eating  spoiled  food  that  smelled  and  tasted 


BACTERIA  41 

good.  Milk,  and  foods  made  from  milk,  are  specially 
likely  to  be  made  poisonous  by  the  growth  of  bacteria 
in  them. 

Bacteria  in  the  Body.  —  Many  kinds  of  bacteria 
which  produce  offensive  decay  are  always  growing  on 
the  skin.  In  the  mouth  bits  of  food,  dead  skin,  and  the 
moisture  of  saliva  form  a  good  soil  in  which  many  kinds 
of  bacteria  flourish,  causing  decay  and  a  bad  smelling 
breath.  Bacteria  are  the  cause  of  decay  in  teeth. 
They  grow  in  the  dead  scales  of  a  dirty  skin,  and  cause 
the  bad  odors  of  an  unwashed  body.  They  grow  abun- 
dantly in  the  intestine,  and  are  the  cause  of  many  forms 
of  indigestion. 

A  few  kinds  of  bacteria  may  grow  in  living  flesh. 
These  are  the  causes  of  most  kinds  of  infectious  dis- 
eases. 

List   of   Infectious   Diseases. — The   common   dis- 
eases which  persons  may  catch  from  others  who  have 
the  same  diseases  number 
about     twenty.      Among 
those    of    which   bacteria 
have  been  proved   to  be 
the  cause  are  diphtheria, 
typhoid  fever,  tuberculo- 
sis,    grippe,     pneumonia, 
lockjaw,    erysipelas,    and 

Bacteria  which  produce  pneumonia. 

most  kinds  of   tonsillitis, 

colds,  and  sore  throats.     Pimples,  boils,  and  all  other 

kinds  of  sores  which  give  off  a  creamy  matter  are 


42  BACTERIA 

often  called  blood  poisoning,  but  they  are  all  caused 
by  bacteria  growing  in  the  flesh. 

Other  examples  of  infectious  diseases  are  mumps 
and  whooping  cough,  and  also  those  diseases  in  which 
the  skin  becomes  spotted  or  broken  out,  such  as  measles, 
German  measles,  scarlet  fever,  smallpox,  and  chicken 
pox.  They  resemble  the  diseases  whose  cause  has  been 
proved  to  be  bacteria. 

Other  Kinds  of  Disease  Germs.  —  A  few  kinds  of 
infectious  diseases  are  caused  by  microscopic  animals 
which  grow  in  the  blood.  Malaria  is  caused  by  a  mi- 
croscopic animal  which  a  kind  of  mosquito  leaves  under 
a  person's  skin  when  it  sucks  his  blood.  Hydrophobia 
is  caused  by  microscopic  animals  which  grow  in  the 
brain. 

Where  Disease  Germs  are  Found.  —  Germs  of 
disease  do  not  grow  naturally  in  the  soil,  or  water,  or 
air,  or  food.  Nearly  all  kinds  grow  only  in  the  bodies 
of  sick  persons  or  animals,  but  they  may  stay  alive 
after  they  have  left  the  bodies  of  the  persons  or  animals 
in  which  they  have  grown.  If  a  person  has  an  infectious 
disease,  it  is  because  he  has  received  living  germs  from 
some  one  who  was  sick  before  he  was.  Every  person 
who  has  an  infectious  disease  is  dangerous  to  others 
around  him,  unless  great  pains  is  taken  to  kill  all  the 
germs  which  come  from  his  body. 

When  a  person  has  an  infectious  disease,  some  of  the 
germs  may  leave  his  body  from  sores  and  wounds,  if 
there  are  any  on  the  skin  ;  but  very  few  germs  leave  the 


BACTERIA  43 

skin  when  it  is  clean  and  sound.  Nearly  all  the  germs 
which  leave  the  body  pass  off  either  from  the  nose  or 
mouth,  or  from  the  intestine,  or  from  the  kidneys.  If 
every  sick  person  should  guard  these  four  gateways  of 
his  body,  few  disease  germs  would  escape  alive,  and 
soon  no  one  would  catch  an  infectious  disease. 

Cleanliness.  —  If  disease  germs  are  not  caught  and 
killed  as  soon  as  they  leave  the  body,  they  may  remain 
alive  for  some  time.  They  are  found  on  everything 
which  has  been  soiled  by  those  who  are  sick  with  in- 
fectious diseases.  They  are  found  in  dirt,  filth,  and 
garbage ;  in  the  dust  and  foul  air  of  houses  and  meet- 
ing places  ;  on  dirty  handkerchiefs,  towels,  bedclothes, 
and  soiled  garments  ;  and  on  forks,  spoons,  dishes,  and 
other  table  furniture  which  have  been  used  by  the  sick. 
The  prevention  of  diseases  may  be  summed  up  in  the 
word  cleanliness. 

By  cleanliness  we  do  not  mean  something  hard  and 
difficult  which  only  a  doctor  can  understand,  but 
simply  keeping  clean  in  the  same  way  that  persons 
do  when  they  expect  company.  It  also  means  keep- 
ing back  yards  and  kitchens  clean  and  neat. 

Board  of  Health.  —  Many  careful  persons  do  not 
know  how  to  prevent  the  spread  of  disease  germs,  and 
many  persons  who  know  how  are  so  careless  that  they 
endanger  the  health  of  the  whole  population  of  a  town. 
For  example,  many  persons  throw  their  garbage,  slops, 
and  sewage  in  a  heap  behind  an  outbuilding,  and  then 
flies  and  the  wind  scatter  disease  germs  from  it  to  a 


44  BACTERIA 

whole  neighborhood.  In  every  state  and  town  men 
are  appointed  as  a  board  of  health,  whose  duty  is  to  com- 
pel all  persons  to  prevent  the  spread  of  disease  germs 
from  themselves  and  their  premises.  Among  the  mat- 
ters which  are  in  their  charge  are  the  disposal  of  slops, 
garbage,  and  sewage,  the  maintenance  of  the  purity 
of  drinking  water  and  food,  and  the  prevention  of  the 
spread  of  disease  germs  from  those  who  have  dangerous 
diseases,  such  as  smallpox  and  diphtheria. 

QUESTIONS 

What  are  infectious  diseases  ? 

Name  some  infectious  diseases. 

By  what  are  infectious  diseases  caused  ? 

What  are  bacteria? 

How  large  are  bacteria  ? 

What  do  bacteria  look  like  ? 

Where  may  bacteria  be  found  ? 

How  do  bacteria  grow  and  multiply  ? 

What  have  bacteria  to  do  with  decay  or  rotting  ? 

Of  what  use  is  decay  ? 

Name  some  other  uses  of  bacteria. 

Why  does  food  keep  fresh  when  it  is  properly  canned  ? 

What  are  ptomaines? 

What  is  one  of  the  reasons  why  spoiled  food  is  sometimes 
poisonous  ? 

What  are  molds? 

What  are  spores  ? 

On  what  part  of  a  mold  plant  do  the  spores  grow  ? 

Why  does  a  piece  of  bread  often  become  moldy  a  few  days 
after  it  is  cut  ? 


BACTERIA 


45 


Where  do  the  bacteria  of  infectious  diseases  grow  ? 

From  what  part  of  a  sick  person's  body  are  disease  germs 
given  off  ? 

What  has  cleanliness  to  do  with  preventing  the  spread  of 
diseases  ? 

What  has  a  board  of  health  to  do  with  preventing  infectious 
diseases  ? 


CHAPTER  V 
ALCOHOL 

Appetites.  —  Cats,  dogs,  and  other  lower  animals  are 
able  to  live  healthy  lives  because  they  are  born  with 
appetites  and  feelings  which  they  follow  in  whatever 
they  do.  Their  feelings  of  hunger  and  thirst,  of  pain 
and  fatigue,  of  joy  and  pleasure,  and  of  anger  and  fear, 
are  some  of  the  guides  by  which  they  live  and  act. 

We  have  the  same  kind  of  appetites  and  feelings  that 
lower  animals  have,  and  we  take  these  feelings  as  our 
guides  in  what  we  do.  But  we  also  have  our  thoughts 
to  guide  us.  An  animal  does  not  think,  but  it  tries 
to  satisfy  its  appetite  as  soon  as  it  feels  a  desire  for 
something.  We  can  think  what  will  happen  if  we 
should  satisfy  an  appetite,  and  we  can  judge  whether 
or  not  it  is  best  to  do  what  we  feel  like  doing.  We  live 
by  means  of  our  thoughts,  as  well  as  our  feelings. 

Pleasure  of  an  Appetite.  —  Satisfying  any  appetite 
gives  us  pleasure  while  we  are  satisfying  it.  Thus 
pleasure  leads  us  to  supply  the  needs  of  our  bodies.  If 
eating  were  a  painful  duty,  many  persons  would  starve 
to  death  rather  than  take  food.  But  eating  is  a  great 
pleasure,  and  many  persons  eat  too  much  because  they 

46 


ALCOHOL  47 

think  of  the  pleasure  of  eating,  and  forget  the  needs  of 
their  bodies.  Appetites  are  not  always  sure  guides, 
for  they  may  be  false  and  harmful. 

False  Appetites.  —  Some  persons  have  appetites  for 
things  which  are  not  good  for  them.  Many  poisons 
seem  to  give  pleasure  at  first,  but  they  cause  sickness 
a  few  hours  or  days  after  they  have  been  taken.  Some 
of  these  poisons  are  alcohol,  tobacco,  and  opium. 
Many  persons  have  appetites  for  them,  and  take  them 
when  they  know  their  danger.  These  appetites  are 
false,  but  they  are  often  more  powerful  than  the  ap- 
petites which  are  true  and  useful.  Men  often  yield 
to  false  appetites  because  they  think  only  of  their 
present  pleasures.  It  is  important  for  you  to  know 
what  these  false  appetites  mean ;  to  understand  the 
danger  from  satisfying  them ;  and  to  know  the  means 
of  preventing  and  overcoming  them. 

Intemperance.  —  Satisfying  a  false  appetite  is  called 
intemperance.  A  person  who  eats  for  pleasure  is  in- 
temperate in  his  eating,  but  by  intemperance  we  usually 
mean  satisfying  an  appetite  for  drinks  which  contain 
alcohol.  These  are  the  drinks  which  are  sold  in  saloons 
and  barrooms,  and  which  are  often  called  strong  drink. 
Men  take  strong  drink  because  they  have  an  appetite 
for  it,  and  do  not  stop  to  think  of  the  harm  that  it 
will  do. 

There  are  many  kinds  of  strong  drink,  but  all  of  them 
contain  a  substance  called  alcohol.  They  are  manu- 
factured from  liquids  which  contain  sugar,  and  are 


48  ALCOHOL 

made  by  changing  the  sugar  to  alcohol.  This  change 
is  produced  by  means  of  plants  called  yeast. 

Yeast.  --Yeast  plants  are  so  small  that  they  cannot 
be  seen  without  a  microscope.  Each  plant  is  a  single 

oval  cell.  A  yeast  cake  that 
may  be  bought  at  a  grocery 
store  consists  of  millions  of 
dried  yeast  plants  mixed  with 
flour  or  meal.  When  the  cake 
is  placed  in  water  which  con- 
tains sugar,  the  cells  grow 
rapidly,  and  new  cells  spring 

Yeast  plants.    Magnified.          £  ,,         .,          .  ,,         ,, 

from  the  sides  of  the  old  ones 

like  buds  from  a  twig.  In  this  way  the  yeast  plants 
increase  in  number  as  rapidly  as  bacteria  do  (p.  36). 

When  yeast  plants  grow,  they  change  sugar  to  al- 
cohol and  carbonic  acid  gas.  The  gas  rises  through  the 
liquid  in  bubbles  which  look  like  bubbles  of  steam  in 
boiling  water.  For  this  reason  the  change  is  called 
fermentation ,  from  the  Latin  word  meaning  boiling. 

Fruit  Juice.  --  The  juice  which  is  pressed  from  sweet 
fruit  contains  sugar,  coloring  matter,  and  flavorings. 
After  it  has  stood  for  a  few  hours,  it  begins  to  ferment. 
The  fermentation  is  caused  by  yeast  plants  which  fall 
into  the  juice  from  the  air.  The  yeast  changes  the 
sugar  to  alcohol,  and  the  fruit  juice  is  then  called  wine. 
Most  wine  is  made  from  grape  juice. 

Fresh  fruit  juice  is  a  wholesome  food  and  drink,  for 
it  is  fruit  from  which  the  skins  and  tough  parts  of  the 


ALCOHOL  49 

pulp  have  been  taken.  If  the  juice  is  heated  and  put 
into  sealed  cans  or  bottles,  it  may  be  kept  for  months 
and  years  without  fermenting,  just  as  canned  food  is 
kept  (p.  39).  In  this  way  fresh  grape  juice,  called  un- 
fermented  wine,  is  preserved. 

Wine.  --There  are  many  kinds  of  fermented  wine, 
but  all  kinds  have  alcohol  in  them.  Some  are  only 
5  per  cent  alcohol.  The  strongest  wine  which  may  be 
made  by  fermentation  contains  about  12  per  cent  of 
alcohol.  Alcohol  is  added  to  some  wines,  such  as  Port 
wine,  and  these  contain  about  20  per  cent  of  alcohol. 
Men  use  wine  for  the  sake  of  the  alcohol  which  is 
in  it. 

Wine  was  the  only  strong  drink  that  men  had  in 
olden  times.  They  knew  that  grapes  were  good  food, 
and  they  used  grape  juice  as  a  drink.  They  noticed 
that  fermented  juice  seemed  stronger,  and  had  a  quicker 
and  more  powerful  effect,  than  fresh  juice.  They  also 
knew  that  many  persons  became  poisoned  by  drinking 
the  fermented  juice,  while  the  fresh  juice  was  harmless. 
But  men  did  not  know  that  the  difference  was  due 
principally  to  the  alcohol  in  the  fermented  juice. 

Some  persons  suppose  that  home-made  wine  will 
not  contain  alcohol  if  no  alcohol  is  put  into  it.  Every 
drink  which  is  made  by  fermentation  contains  alcohol. 
Home-made  wines  contain  alcohol,  and  are  as  harmful 
as  those  which  are  bought. 

Cider.  —  Wine  made  from  apple  juice  is  called  cider. 
Apple  juice  begins  to  ferment  within  a  few  hours  after 

GEN.    EYG.  —  4 


50 


ALCOHOL 


it  is  pressed  out,  and  cider  which  is  only  a  few  days  old 
will  contain  enough  alcohol  to  be  harmful. 

Vinegar.  —  If  a  fruit  juice  contains  only  a  little  sugar, 
it  will  become  sour  when  it  ferments.  This  is  because 
bacteria  grow  in  the  juice  with  the  yeast,  and  change  its 
alcohol  to  a  sour  substance  called  acetic  acid.  After 
cider  has  fermented  for  some  weeks,  all  of  its  alcohol 
becomes  acetic  acid,  and  the  liquid  is  then  called  vinegar, 
from  two  Latin  words  meaning  sour  wine.  A  great 
deal  of  vinegar  is  made  from  the  juice  of  grapes  and 
apples. 

Beer.  —  Alcoholic  drinks  are  also  made  by  boiling 
sweet  substances  in  water,  and  fermenting  the  liquid. 
These  drinks  are  called  beer.  Root  beer  and  birch  beer 
are  often  made  at  home,  but  both  of  these  drinks 
contain  alcohol,  and  their  use  is  harmful. 

, ,        The      beer 

which  is  sold  in 
barrooms  is 
made  from 
grain,  princi- 
pally barley. 
The  grain  is  first 
made  wet,  and 
is  then  spread 
on  a  floor  until 
it  sprouts.  The 
growing  stems  change  some  of  the  starch  of  the  grain  to 
sugar.  The  grain  and  its  sprouts  are  then  called  malt. 


Malt' 


ALCOHOL  51 

Beer  is  made  by  boiling  malt  with  hops,  and  fer- 
menting the  liquid.  It  contains  about  5  per  cent  of 
alcohol.  Some  kinds  of  beer  also  contain  a  small 
amount  of  food  substances  which  were  dissolved  from 
the  malt.  But  the  malt  which  is  not  dissolved  by  the 
boiling  contains  most  of  the  food  substances  of  the  grain. 
It  is  usually  dried  and  sold  as  food  for  cattle.  When 
grain  is  made  into  beer,  men  get  the  part  which  is 
harmful,  and  cattle  get  the  part  which  is  a  valuable  food. 

The  people  of  the  United  States  use  a  greater 
quantity  of  beer  than  of  any  other  kind  of  strong  drink. 
Over  a  billion  gallons  are  manufactured  each  year. 
This  is  equal  to  a  large  glassful  for  each  inhabitant  each 
day  of  the  year.  Sixty  millions  of  bushels  of  grain  are 
used  in  making  the  beer.  This  is  enough  grain  to  feed 
all  the  inhabitants  of  the  country  for  nearly  a  month. 

Distilled  Drinks.  —  Alcohol  boils  at  a  cooler  tem- 
perature than  water.  When  a  mixture  of  alcohol  and 
water  is  heated,  the  alcohol  will  rise  as  a  vapor  before 
the  water  is  hot  enough  to  form  much  steam.  If  the 
vapor  is  collected  and  cooled,  it  will  become  a  liquid 
again.  The  first  liquid  which  is  collected  from  the 
heated  mixture  will  be  mostly  alcohol.  In  this  way 
alcohol  may  be  separated  from  water.  Separating 
alcohol  from  other  substances  by  boiling  the  mixture 
and  cooling  the  vapor  is  an  example  of  distillation. 

If  any  liquid  containing  sugar  is  fermented  and  dis- 
tilled, the  liquor  which  is  obtained  will  be  rich  in 
alcohol.  Brandy  is  an  alcoholic  drink  which  is  made 


52  ALCOHOL 

by  distilling  wine.  Whisky  is  made  by  distilling  the  fer- 
mented liquid  from  boiled  grain.  Rum  is  made  by 
distilling  fermented  molasses.  Each  of  these  drinks  is 
about  half  alcohol. 

A  great  deal  of  what  is  called  brandy  and  whisky 
is  made  by  boiling  fruit  skins,  spoiled  fruit,  potato 
peelings,  and  other  waste  substances  containing  sugar 
or  starch,  and  then  fermenting  and  distilling  the  liquid. 
This  makes  a  cheap  kind  of  strong  drink.  This  drink 
may  be  made  to  taste  and  look  like  the  more  costly 
kinds,  but  it  is  more  poisonous  than  the  drinks  which 
are  made  from  good  fruit  and  grain. 

Uses  of  Alcohol.  —  Pure  alcohol  is  a  liquid  which 
looks  like  water.  It  will  dissolve  many  substances 
which  water  will  not  dissolve,  and  for  this  reason  it  is 
largely  used  in  manufacturing.  Meat  placed  in  it  will 
not  decay,  and  so  it  is  used  in  schools  and  colleges  for 
preserving  specimens.  It  will  burn  with  a  hot  flame 
without  smoke,  and  so  it  is  often  used  for  heating  and 
cooking.  Its  mixture  with  air  will  explode,  and  so  it 
is  sometimes  used  in  engines  in  the  place  of  gasoline. 

There  are  two  kinds  of  alcohol  in  common  use.  One 
kind  is  made  from  wood,  and  is  used  in  manufacturing, 
but  it  is  too  poisonous  to  be  used  as  a  drink.  The  other 
kind  in  common  use  is  that  made  from  grain. 

Grain  alcohol  is  taxed  by  the  government.  It  is 
sometimes  mixed  with  wood  alcohol  and  other  sub- 
stances which  give  it  a  bad  taste  and  make  it  unfit  for 
drinking.  It  is  then  called  denatured  alcohol.  This 


ALCOHOL  53 

kind  is  not  taxed,  and  is  much  cheaper  than  pure  grain 
alcohol.  For  this  reason  it  is  the  kind  which  is  used  for 
most  purposes  except  drinking. 

Regulation  of  the  Sale  of  Alcoholic  Drinks.  --The 
use  of  strong  drink  is  dangerous,  and  most  states  have 
laws  which  forbid  any  one  to  sell  it  without  a  permit 
or  license  from  the  government.  The  government 
charges  a  large  sum  of  money  for  a  license,  but  the 
money  which  is  received  does  not  pay  for  more  than  a 
small  part  of  the  harm  which  comes  from  the  sale  of 
the  drink.  Some  towns  and  states  have  laws  forbid- 
ding the  sale  of  any  kind  of  alcoholic  liquor  for  drinking 
purposes.  These  laws  are  called  prohibition  laws. 
The  reason  for  making  them  is  that  many  persons  get 
such  strong  appetites  for  strong  drink  that  they  cannot 
help  taking  it,  even  when  they  know  that  they  are 
doing  great  harm  to  themselves,  and  to  their  families 
and  neighbors. 

Drunkenness.  —  Strong  drink  produces  two  kinds 
of  harmful  effects  on  those  who  take  it.  One  kind  of 
harm  is  that  which  comes  on  within  a  few  moments 
after  the  drink  is  taken.  This  effect  is  called  drunk- 
enness, or  intoxication.  Drunkenness  is  a  severe  sick- 
ness of  both  the  body  and  the  mind.  It  harms  a 
person  like  any  other  form  of  sickness. 

A  person  who  is  drunk  is  not  in  his  right  mind.  He 
is  often  quarrelsome  and  cruel.  He  cannot  attend  to 
his  business,  and  often  allows  his  family  to  suffer.  He 
will  often  steal,  and  lie,  and  cheat,  and  will  commit 


54  ALCOHOL 

crimes  which  he  would  not  commit  if  he  were  in  his  right 
mind.  About  half  of  the  prisoners  in  the  jails  of  the 
United  States  are  there  as  a  result  of  strong  drink. 
Drunkenness  is  a  crime,  and  in  many  towns  and  cities 
those  who  are  seen  drunk  on  the  streets  are  arrested 
and  punished. 

The  other  kind  of  harmful  effect  which  is  produced  by 
alcoholic  drinks  is  a  slow  poisoning  of  the  whole  body 
and  mind.  This  effect  may  come  from  taking  small 
quantities  of  drink  often,  even  though  the  person  does 
not  get  drunk. 

The  effects  of  alcohol  on  each  part  of  the  body  will 
be  described  as  each  of  the  organs  is  studied. 

Alcohol  a  Stimulant.  —  Alcohol  acts  like  a  whip  to 
the  mind  and  the  body.  The  old  Romans  called  a 
whip  a  stimulus,  and  for  this  reason  alcohol  is  called  a 
stimulant.  A  whip  does  not  make  a  person  or  an  animal 
strong.  There  are  far  better  ways  of  getting  a  man  to 
work  than  by  driving  him  with  a  whip,  or  with  a  stim- 
ulant. 

Alcohol  rouses  a  person  up,  and  he  may  then  think 
that  his  strength  is  increased  because  he  feels  like 
doing  something.  But  the  drink  really  disturbs  him 
in  his  work,  just  as  whipping  a  boy  in  school  every  few 
minutes  would  disturb  him  in  getting  his  lessons.  A 
difference  between  a  whipping  in  school  and  a  stimu- 
lation with  alcohol  is  that  the  whipping  causes  pain 
at  once ;  but  alcohol  dulls  the  mind,  and  prevents  the 
harm  from  being  felt  until  afterward.  This  is  the 


ALCOHOL  55 

great  danger  from  taking  alcohol,  for  it  deceives  the 
drinker,  and  makes  him  think  that  he  is  being  helped, 
when  he  is  really  being  harmed. 

Alcohol  a  Narcotic. --The  mind  of  a  man  who  is 
stimulated  with  alcohol  is  benumbed  and  cannot  act 
right,  even  though  it  tries  to  do  so.  For  this  reason 
alcohol  is  called  a  narcotic,  from  a  Greek  word  meaning 
to  make  numb. 

Why  Men  Drink.  —  Men  give  many  reasons  for 
drinking.  Some  say  that  they  drink  to  keep  warm, 
and  others  to  keep  cool.  Some  drink  to  make  them- 
selves think,  and  others  to  keep  themselves  from  think- 
ing. Some  drink  in  order  to  go  to  sleep,  and  others 
to  keep  awake.  These  are  only  excuses  for  drinking. 
Men  drink  because  they  are  mistaken  with  their  ap- 
petites, and  suppose  that  their  feelings  always  show 
what  their  bodies  need_ 

Most  drinkers  suppose  that  they  can  take  a  little 
alcohol  without  harm,  and  that  they  can  stop  drinking 
before  they  begin  to  be  harmed.  This  is  not  so.  The 
alcohol  benumbs  their  thoughts  and  feelings.  They 
cannot  judge  of  the  harm  which  they  are  doing  to 
themselves,  but  they  often  keep  on  drinking  and  injure 
themselves  for  life.  It  is  not  safe  to  begin  to  take  any 
kind  of  strong  drink  at  all. 

Another  reason  why  men  drink  is  because  they  meet 
their  friends  in  saloons  and  barrooms.  There  they 
find  warmth,  easy  chairs,  and  games  which  they  may 
use  free*  of  charge  if  they  buy  strong  drink.  A  great 


56  ALCOHOL 

many  men  go  to  saloons  and  barrooms  because  of  these 
pleasures,  and  in  this  way  they  finally  learn  to  take 
strong  drink  when  they  did  not  care  at  all  for  it  at  first. 

One  method  of  keeping  men  away  from  saloons  and 
barrooms  is  to  provide  them  with  meeting  places  where 
they  can  be  as  comfortable  as  in  the  drinking  places. 
Some  churches  and  temperance  societies  are  trying  to 
do  this  kind  of  work. 

The  Custom  of  Treating.  --The  custom  of  inviting 
friends  to  drink  is  one  of  the  principal  causes  which 
lead  men  to  take  strong  drink.  Those  who  drink 
usually  treat  their  friends,  and  drink  when  they  are 
invited  by  others,  and  in  this  way  they  drink  when  they 
do  not  wish  to.  The  custom  of  treating  also  leads  men 
to  take  far  more  liquor  than  they  had  expected  to  take. 
If  each  man  should  buy  his  drink  in  the  same  way  that 
he  buys  his  bread  and  shoes,  there  would  not  be  nearly 
so  much  drinking  as  there  is. 

It  is  the  custom  for  young  persons  to  treat  each  other 
to  ice  cream,  soda  water,  and  candy,  and  thus  they  grow 
up  expecting  to  carry  out  the  custom  of  treating  all 
through  their  lives.  It  is  a  fine  thing  to  be  generous, 
and  to  divide  what  we  have  with  others,  but  it  is  wrong 
to  divide  simply  for  the  sake  of  appearing  generous. 
There  is  no  more  reason  why  boys  and  girls  should  treat 
each  other  to  soda  water  than  there  is  for  them  to  treat 
each  other  to  pencils  and  books.  Temperance  work 
would  be  greatly  helped  if  the  custom  of  treating  were 
entirely  abolished. 


ALCOHOL  57 

QUESTIONS 
t 

Of  what  use  are  the  appetites  ? 
Name  some  false  appetites. 
What  is  intemperance? 
What  is  yeast  ? 

;What  is  fermentation? 

What  substances  are  produced  by  yeast  in  a  fermenting 
liquid  ? 

How  is  wine  made  ? 

Why  is  fermented  wine  harmful,  while  the  fruit  juice  of  which 
it  is  made  is  a  good  food  ? 

What  harmful  substance  does  cider  contain  ? 

How  is  vinegar  made  ? 

What  is  malt? 

How  is  beer  made  ? 

How  much  alcohol  is  in  beer  ? 

How  is  whisky  made  ? 

Name  some  uses  of  alcohol. 

»«/'• 
What  is  wood  alcohol  ? 

Why  is  it  right  to  have  laws  regulating  the  sale  of  strong 
drink? 

What  are  prohibition  laws? 

What  is  meant  by  drunkenness  ? 

What  is  a  stimulant? 

What  is  a  narcotic  ? 

Explain  in  what  respect  alcohol  is  both  a  stimulant  and  a 
narcotic. 

Name  some  ways  in  which  the  habit  of  drinking  alcoholic 
liquors  is  formed. 

What  harm  is  done  by  the  custom  of  treating  ? 


CHAPTER  VI 


NARCOTICS 

Tobacco.  -  -  Tobacco  is  a  narcotic  that  was  first  used 
by  the  American  Indians.  The  early  settlers  and  ex- 
plorers sent  ship  loads 
of  it  home,  and  its  use 
spread  quickly  over  all 
the  known  world.  Mil- 
lions of  pounds  are  now 
raised  every  year  in  the 
United  States,  and  mil- 
lions more  are  brought 
into  the  country. 
There  are  a  greater 
number  of  stores  and 
stands  for  the  sale  of 
tobacco  than  there  are 
for  the  sale  of  any  other 
article. 

Tobacco  plants.  A  tobacco  plant  grows 

about  as  tall  as  a  man.  It  has  a  central  stalk  which 
bears  large,  broad  leaves.  The  leaves  are  gathered 
and  dried,  and  are  manufactured  into  smoking  tobacco, 
chewing  tobacco,  and  snuff. 

58 


NARCOTICS  59 

Nicotine.  -  -  Tobacco  contains  a  substance  called 
nicotine,  which  is  a  powerful  poison.  Two  or  three 
drops  of  pure  nicotine  would  make  a  man  dangerously 
sick.  Men  use  tobacco  for  the  sake  of  this  poison. 
The  quantity  of  tobacco  which  is  usually  taken  at  once 
contains  enough  nicotine  to  kill  a  man,  if  all  of  it  should 
be  swallowed  at  one  time.  The  reason  why  those  who 
use  tobacco  are  not  killed  by  it  is  that  they  do  not 
swallow  much  of  the  nicotine. 

Why  Men  use  Tobacco.  —  Men  use  tobacco  because 
of  its  narcotic  effects.  They  say  that  it  quiets  them 
and  makes  them  feel  restful.  If  it  were  of  use  in  this 
way,  it  would  be  used  in  medicine  and  would  be  given 
to  women  and  children,  for  they  need  quieting  medicines 
as  much  as  men  need  them.  But  it  is  too  poisonous 
to  be  used  in  medicine,  and  no  one  now  uses  it  in  this 
way. 

The  real  reason  why  men  use  tobacco  is  because  they 
form  a  habit  of  its  use.  They  take  it  for  pleasure  only, 
and  to  satisfy  a  false  appetite  for  it. 

Effects  of  Tobacco. -- Tobacco  produces  a  quick 
form  of  poisoning,  and  a  slow  form.  The  quick  form 
of  poisoning  is  a  feeling  of  stomach  sickness,  with  pale- 
ness and  weakness.  Most  persons  are  made  sick  when 
they  first  try  to  smoke  or  chew.  The  body  may  be- 
come somewhat  used  to  the  poisonous  effects  of  tobacco, 
but  even  the  greatest  smokers  and  chewers  become  sick 
when  they  take  a  little  more  than  usual  at  one  time. 

When  tobacco  is  used  day  after  day,  it  produces  a 


60  NARCOTICS 

slow  poisoning  of  the  heart,  lungs,  muscles,  eyes,  and 
other  parts  of  the  body.  These  effects  will  be  men- 
tioned when  the  separate  organs  are  studied. 

Tobacco  and  Young  Persons.  —  Tobacco  has  a  far 
greater  poisonous  effect  on  young  persons  than  on  those 
who  are  grown.  Many  boys  think  that  while  they  are 
smoking,  they  look  like  grown-up  persons.  Using  it 
prevents  them  from  growing  up  strong  and  healthy. 
After  a  person  has  got  his  growth,  he  can  stand  an 
amount  of  poisoning  which  would  make  a  young  per- 
son dangerously  sick.  Young  persons  do  not  have  the 
power  of  overcoming  the  poisonous  effects  of  tobacco, 
just  as  they  do  not  have  the  power  to  do  hard  work 
with  their  muscles. 

Cigarettes.  —  Many  young  persons  suppose  that 
cigarettes  are  only  slightly  poisonous.  A  cigarette 
is  not  so  poisonous  as  a  large  cigar,  or  a  pipe-full  of 
tobacco,  because  it  is  smaller  than  they.  But  the  small 
quantity  of  nicotine  that  is  in  a  cigarette  is  more 
poisonous  to  a  boy  than  the  large  amount  of  nicotine 
in  a  cigar  or  pipe  is  to  a  grown  man.  The  use  of  ciga- 
rettes by  boys  is  so  dangerous  that  many  states  have 
laws  forbidding  their  sale  to  those  who  are  under 
eighteen  years  of  age. 

Opium.  —  The  dried  juice  of  poppy  plants  is  a  gummy 
substance  called  opium.  It  contains  morphine  and 
other  substances  which  are  poisons.  Opium  is  a  valu- 
able drug  which  is  used  in  medicine  to  ease  pain  and 
to  produce  sleep.  It  is  a  strong  narcotic  poison,  and 


NARCOTICS  61 

its  use  is  so  dangerous  that  only  skilled  physicians 
know  how  to  give  it  safely.  Yet  many  persons  who 
begin  to  take  it  for  pain  form  a  habit  of  its  use,  just 
as  men  form  a  habit  of  using  alcohol  or  tobacco. 
The  opium  habit  is  extremely  dangerous,  and  those 
who  form  it  seldom  live  more  than  a  few  months  or 
years. 

Opium  in  Medicines.  —  Medicines  are  often  ad- 
vertised in  newspapers  and  almanacs  as  soothing 
sirups,  or  as  cough  cures,  or  as  pain  killers.  Many 
of  these  medicines  contain  opium,  and  it  is  the  opium 
which  produces  their  quieting  effects.  The  medicines 
will  not  cure  a  sickness,  but  they  will  make  it  worse. 
What  they  really  do  is  to  dull  the  feeling  of  pain,  and 
the  person  who  takes  them  may  then  feel  better  for 
a  time,  but  the  sickness  goes  on  just  as  if  the  medicines 
had  not  been  taken. 

Many  lives  are  lost  each  year  because  the  sick  take 
opium  or  morphine,  and  then  suppose  that  they  are 
out  of  danger  because  they  feel  no  pain.  A  pain  is 
only  a  sign  of  sickness.  If  you  have  a  bad  pain  and 
it  is  taken  away  by  the  use  of  opium  or  morphine,  you 
need  a  good  nurse  or  doctor  to  look  after  you,  for  the 
narcotic  dulls  your  mind  and  feelings,  and  you  cannot 
judge  for  yourself  how  ill  you  are. 

Headache  Cures.  —  Many  medicines  which  are 
sold  for  the  cure  of  headache  contain  drugs  which  make 
the  heart  extremely  weak.  These  drugs  do  not  cure 
the  headache,  and  their  use  is  dangerous. 


62  NARCOTICS 

Alcohol  in  Medicines.  —  A  great  many  of  the  bitters 
and  medicines  which  are  advertised  in  newspapers  and 
almanacs  contain  as  much  alcohol  as  strong  wine. 
The  alcohol  is  put  into  the  medicines  to  keep  them 
from  spoiling.  When  a  person  takes  a  drink  of  one  of 
these  medicines,  he  takes  as  much  alcohol  as  he  would 
take  if  he  should  buy  a  drink  of  liquor  at  a  saloon. 
Many  persons  keep  Jamaica  Ginger  in  the  house  for 
use  in  stomach  troubles ;  but  it  is  only  alcohol  flavored 
with  ginger.  The  laws  of  many  states  now  require 
that  the  label  on  each  bottle  of  advertised  medicines 
shall  tell  what  substances  are  in  the  bottle. 
.  Drugs  and  Health.  —  Many  persons  suppose  that 
some  drugs  will  make  them  strong,  that  some  will 
drive  away  diseases,  and  that  others  will  make  their 
complexions  fair.  This  is  not  so.  Nearly  all  drugs  are 
poisons,  and  only  trained  doctors  know  how  to  use 
them.  But  giving  drugs  is  only  a  small  part  of  what 
a  doctor  does  to  cure  a  sick  person.  He  tries  to  remove 
the  cause  of  the  sickness.  For  example,  if  a  person  is 
sick  because  he  is  tired  from  overwork,  the  doctor  does 
not  give  him  drugs,  but  tells  him  how  to  work  and  rest. 
The  things  which  cure  diseases  as  well  as  prevent  them 
are  not  drugs,  but  they  are  such  things  as  right  eating 
and  drinking,  proper  breathing,  cleanliness,  exercise, 
rest,  and  sleep.  In  the  prevention  and  cure  of  sickness 
a  knowledge  of  the  use  of  drugs  is  of  far  less  value 
than  a  knowledge  of  hygiene  and  of  right  living. 


NARCOTICS  63 


QUESTIONS 

Who  were  the  first-  users  of  tobacco  ? 
What  is  nicotine? 

What  are  the  effects  of  nicotine  on  the  body  ? 
What  effect  does  tobacco  have  on  a  person  who  takes  more 
than  he  usually  takes  ? 

What  effect  does  tobacco  have  on  young  persons  ? 

Why  are  cigarettes  often  more  harmful  than  large  cigars  ? 

What  is  opium  ? 

What  is  morphine  ? 

What  substance  do  soothing  sirups  usually  contain  ? 

What  is  the  danger  from  the  use  of  opium  in  treating  a  pain  ? 

What  harmful  effects  do  headache  cures  often  have  ? 

What  harmful  substance  does  Jamaica  Ginger  contain  ? 

Of  what  value  are  drugs  in  making  a  person  strong  ? 


CHAPTER  VII 


BONES  AND   JOINTS 


The  Skeleton.  —  The  flesh 
is  supported  by  a  bony 
framework  called  the  skele- 
ton. The  bones  weigh  about 
one  seventh  as  much  as  the 
whole  body.  They  give 
firmness,  stiffness,  and  shape 
to  the  body. 

The  size  of  the  skeleton 
fixes  the  size  of  the  body. 
If  the  bones  are  long  and 
large,  the  body  will  be  tall 
and  large,  but  if  they  are 
small  and  short,  the  body 
will  be  small  in  size. 

A  bone  is  shaped  some- 
what like  the  part  of  the 
body  in  which  it  lies.  The 
most  of  the  bones  of  the 
arms,  legs,  hands,  and  feet 
are  long  and  straight,  like 
rods,  and  the  most  of  the 
bones  of  the  head  are  flat 
and  thin,  like  sheets  of  card- 

64 


Skull 

Jaw  bone 
Spine 
Collar"  bone 

Shoulder  blade 


Ribs 


Hunter  us 


Tibia 
Fibula 


The  skeleton. 


BONES   AND  JOINTS 


board.  The  picture  of  a  skeleton  looks  something  like 
the  picture  of  a  very  thin  man,  for  the  shape  of  every 
part  of  the  body  is  outlined  in  bone. 

Names  of  Bones.  —  There  are  about  two  hundred 
separate  bones  in  the  body,  and  each  one  has  a  name. 
The  long  bone  which 
reaches  from  the 
shoulder  to  the 
elbow  is  called  the 
humerus.  Two  long 
bones  extend  from 
the  elbow  to  the 
wrist.  The  one  on 
the  thumb  side  of 
the  arm  is  called  the 
radius,  and  the  one 
on  the  little  finger 
side  is  called  the 
ulna. 

Joints.  --  B  ones 
are  joined  together  in  such  a  way  that  most  of  them 
may  turn  at  the  joints.  The  elbow  joint  is  formed 
by  the  rounded  end  of  the  humerus  fitting  into  a 
rounded  notch  in  the  ulna.  The  arm  can  bend  at  the 
elbow  back  and  forth  in  only  one  direction,  for  the 
socket  of  the  bones  is  long,  and  is  rounded  in  only 
one  direction,  like  a  door  hinge.  The  joint  at  the 
shoulder  is  shaped  like  half  a  ball,  and  allows  the  arm 
to  turn  in  every  direction. 

GEN.    HYG. — 5 


X-ray  photograph  of  the  bones  of  the  face. 


66 


BONES   AND   JOINTS 


X-ray  photograph  of  the  elbow  of  a  grown  man. 

The  backbone  is  made  up  of  twenty-six  bones  which 
are  piled  one  upon  another  like  a  long  string  of  spools. 

They  are  joined 
together  by  tough 
pads  of  flesh  in 
such  a  way  that 
the  whole  string 
of  bones  may  bend 
somewhat,  al- 
though the  motion 
is  slight  between 
any  two  bones. 

The  edges  of  the 
bones  of  the  skull 
are  very  irregular, 
and  are  fitted  to- 


x-ray  photograph  of  the    elbow  of  a  three- 
year-old  child. 


BONES   AND  JOINTS 


67 


3AOOTH  SURFACE? 
OF  JOINT 


gether  like  a  dove-tailed  joint  in  a  box.  These  bones 
have  only  a  very  slight  motion  at  their  joints.  The 
only  bone  of  the  head  which  can  move  freely  is  the 
lower  jaw. 

Ligaments.  - 
Bones  are  joined 
together  at  the 
joints  by  strong 
connective  tissue 
bands  called  liga- 
ments. What  we 

call      gristle      on      a  •     Ligaments  of  the  shoulder  joint  of  a  sheep. 

soup  bone  is  composed  mostly  of  ligaments.  Many  of 
the  tendons  of  muscles  are  also  fastened  to  the  bones 
at  the  joints,  and  act  as  ligaments  to  hold  the  bones 

in  place. 

The  ligaments  of  a 
shoulder,  or  elbow,  or 
other  joint  which  may 
be  freely  moved,  sur- 
round the  bones  like  a 
collar,  thus  forming  a 
pocket  within  which 
the  ends  of  the  bones 
turn.  Each  pocket 
contains  a  liquid, 


Tendons  fastened  to  the  ligaments  of  the 
shoulder  joint  of  a  sheep. 


called  the  synomal  fluid,  whose  use  is  to  make  the 
ends  of  the  bones  smooth  and  slippery,  like  an  oiled 
hinge. 


68  BONES  AND   JOINTS 

The 'bones  of  the  wrist  are  small  and  rounded,  like 
pebble  stones.  Ligaments  of  connective  tissue  bind 
them  together  so  firmly  that  they  seem  like  a  single 
bone.  Yet  the  ligaments  will  stretch  slightly  when 
the  wrist  is  struck  or  strained,  and  the  wrist  will  not 
be  broken  so  easily  as  it  would  if  composed  of  a  single 
bone. 

Sprained  Joints.  —  When  a  joint  is  turned  too  far, 
or  in  the  wrong  direction,  the  ligaments  are  stretched 
and  torn.  The  joint  then  becomes  sore  and  swollen, 
and  the  skin  around  it  may  become  blue  from  the  bleed- 
ing of  the  torn  ligaments. 

We  may  help  a  person  who  has  a  sprained  joint  by 
soaking  the  joint  in  hot  water  for  an  hour  or  two. 
Then  a  bandage  wound  snugly  around  the  joint  will 
help  to  prevent  the  pain  and  swelling  from  returning. 
After  a  rest  of  two  or  three  days  a  sprained  joint  will 
be  helped  by  moving  it,  even  if  the  motion  causes  some 
pain.  If  the  joint  is  not  moved  early,  the  torn  liga- 
ments may  grow  together  too  short,  or  may  grow  fast 
to  the  bone,  and  the  joint  will  then  be  stiff  and  painful 
for  a  long  time. 

Dislocated  Bones.  —  When  the  ends  of  the  bones  in  a 
joint  slip  past  each  other,  we  say  that  the  bones  are  out 
of  joint,  or  dislocated.  Putting  a  bone  out  of  joint 
tears  some  of  the  ligaments  of  the  joint. 

Boys  sometimes  put  their  fingers  out  of  joint  in 
playing  baseball.  If  a  finger  is  out  of  joint,  you  can 
put  it  back  in  place  by  pulling  upon  it. 


BONES  AND  JOINTS 


69 


If  a  large  joint,  such  as  an  elbow,  is  dislocated,  bind 
the  limb  to  the  body,  or  to  a  narrow  board,  so  as  to 
keep  the  injured  parts  at  rest.  You  can  then  move 
the  person  home  without  danger. 

Structure  of  Bones.  —  The  shafts  of  long  bones, 
such  as  those  in  the  arms  and  legs,  are  hollow,  like  the 
frame  of  a  bicycle. 
Their  ends  are  like 
a  fine  honeycomb, 
or  sponge,  covered 
with  a  shell  of  hard 
bone.  This  ar- 
rangement makes 


A  long  bone  sawed  in  two. 


them  light  and  yet  strong.  A  long  bone  is  about 
twice  as  strong  as  an  oak  stick  of  the  same  size. 

A  flat  bone,  like  one  from  the  head,  is  composed  of 
two  sheets  of  hard  bone,  separated  by  a  network  of 
spongy  bone.  By  this  means  the  parts  inside  of  the 
head  are  protected  in  a  much  better  manner  than  if 
the  bone  were  a  single  sheet. 

A  dried  bone  is  two  thirds  lime.  Soaking  a  bone 
in  a  mixture  of  one  part  of  hydrochloric  acid  in  ten 
parts  of  water  will  remove  the  lime,  leaving  the  bone 
so  soft  that  it  may  be  tied  in  a  knot.  Burning  a  bone 
will  remove  the  connective  tissue,  and  leave  the  lime 
in  the  exact  shape  of  the  bone. 

Bone  Cells.  —  Bone  is  composed  of  cells  of  connective 
tissue,  arranged  in  circles  around  the  blood  tubes.  The 
cells  have  small  bodies,  and  a  great  number  of  fine 


BONES  AND   JOINTS 


Bone  cells. 

quantity  of  lime 
from  the  blood  for 
its  own  use,  but 
bone  cells  take  a 
great  deal  of  lime, 
and  use  it  for  the 
benefit  of  the  whole 
body. 

Cartilage.  -  -  A 
thin,  tough  pad  of 
gristle,  called  car- 
tilage, covers  the 
end  of  each  bone 
in  a  movable  joint. 
A  layer  of  cartilage 
also  joins  the  bones 


branches.  They 
are  the  living  parts 
of  bones.  Their 
special  work  is  to 
take  lime  from  the 
blood,  and  to  fix  it 
among  their 
branches  in  order 
to  make  the  bone 
hard  and  stiff. 
Every  cell  of  the 
body  takes  a  small 


X-ray  photograph  of  the  hand  of  a  thirteen- 
year-old  child. 


BONES  AND   JOINTS 


together  in  immovable  joints.  Cartilage  is  like  bone 
which  contains  only  a  little  lime.  Each  bone  of  a 
very  young  child'  consists  largely  of  cartilage  which 
takes  up  lime  and 
becomes  true  bone 
as  the  child  grows. 
Bone  Deformi- 
ties. —  While  the 
bones  are  young 
and  soft,  they  may 
bend  slightly  if 
pressure  is  put 
upon  them.  If  the 
pressure  is  kept  up 
day  after  day,  the 
bones  may  grow 
crooked  and  de- 
f  ormed .  The 
weight  of  the  body 
may  bend  the 
bones  of  a  poorly 
nourished  baby, 
thus  producing 
bow  legs.  The 
backbone  may  grow  crooked  from  sitting  at  a  desk 
which  does  not  fit  the  back.  If  a  child  has  its  nose 
so  stopped  up  that  it  has  to  breathe  through  its 
mouth,  the  bones  of  the  upper  jaw  may  be  com- 
pressed sidewise  so  much  that  the  upper  teeth  pro- 


X-ray  photograph  of   the  hand  of  an  eight- 
year-old  child. 


72  BONES  AND    JOINTS 

ject  beyond  the  lips.  Most  deformities  of  the  body 
may  be  prevented  by  attention  to  the  bones  while  the 
child  is  growing. 

Small  children  who  are  fed  with  only  bread  and 
coffee,  or  with  other  improper  food,  may  not  take  enough 
lime  into  their  bodies  to  make  their  bones  hard.  These 
children  often  grow  up  with  small  and  deformed  bones. 
The  deformities  may  be  prevented  by  giving  the 
children  a  variety  of  nourishing  food,  such  as  fresh  vege- 
tables and  meat. 

Bone  Diseases.  -  -  The  solid  part  of  a  bone  contains 
blood  tubes,  and  grows  in  the  same  way  that  flesh 
grows.  Disease  germs  may  enter  a  bone,  and  cause 
it  to  become  swollen  and  softened.  Hip  joint  disease 
is  a  form  of  lameness  caused  by  the  germs  of  tuber- 
culosis growing  in  and  around  the  hip  joint.  Hunch- 
back is  caused  by  tuberculosis  germs  growing  in  some 
of  the  bones  of  the  upper  part  of  the  backbone,  and 
causing  them  to  become  so  soft  that  the  weight  of  the 
body  flattens  them. 

Repair  of  Injured  Bones.  —  A  bone  is  covered  with 
a  tough  skin,  called  periosteum,  which  helps  to  form 
new  bone  when  the  old  bone  is  injured  or  diseased. 
When  a  bone  is  broken,  the  connective  tissue  cells 
form  new  cells,  and  fill  the  space  between  the  two  ends 
with  soft  flesh.  The  new  flesh  then  takes  up  lime,  and 
in  a  month  or  two  it  becomes  stiff  bone. 

How  Bones  become  Broken. — The  usual  way  in 
which  a  person  breaks  a  bone  is  by  falling  upon  it  in 


BONES   AND   JOINTS 


73 


such  a  way  that  his  weight  comes  upon  it  like  a  sudden 
blow.  A  child's  body  does  not  fall  with  so  much  force 
as  the  body  of  a 
heavy  man,  and  so 
a  child  may  not  be 
harmed  by  a  fall 
which  would  break 
the  bones  of  a  man. 

The  bones  of  a 
child  do  not  con- 
tain so  much  lime 
as  the  bones  of  a 
grown  person,  and 
they  may  safely 
bend  more  than 
the  bones  of  a 
man. 

Too  much  lime 
in  a  bone  makes  it 
weak  and  brittle,  like  the  stem  of  a  clay  pipe.  Bones 
take  up  more  and  more  lime  as  a  person  grows  older, 
and  old  persons  often  get  broken  bones  from  falls 
which  are  too  slight  to  harm  a  young  man. 

What  to  do  for  a  Broken  Bone.  —  A  broken  bone  is 
painful,  and  the  flesh  near  the  break  is  usually  bluish 
because  of  the  bleeding  of  the  bone.  A  break  may  be 
only  a  crack  in  a  bone,  and  may  appear  like  a  bad 
sprain.  It  is  often  impossible  to  tell  a  break  from 
a  sprain  unless  an  X-ray  photograph  of  the  bone 


Wrist  of  a  grown  man,  showing  bone  broken 
by  cranking  an  automobile. 


74 


BONES   AND   JOINTS 


is  taken.     It  is  important  to  know  whether  or  not  a 
bone  is  broken,  for  rubbing  and  moving  the  injured 

part  will  harm  a  broken  bone, 
but  will  help  a  sprain. 

If  a  bone  is  broken  in  two,  it 
may  be  bent  at  the  broken  spot. 
A  slight  motion  will  cause  great 
pain  by  rubbing  the  broken  ends 
together. 

You  can  help  a  person  who 
has  a  broken  bone  by  binding  a 
stick  or  a  thin  board  along  the 
whole  length  of  the  limb,  using 
handkerchiefs  for  bandages. 
After  you  have  done  this,  the 
bones  cannot  move,  and  you  can 

A  broken  arm  bandaged.        ^^   ^    mjured   person    home 

without  danger  to  the  broken  part. 

QUESTIONS 

What  is  the  skeleton? 
Name  the  principal  bones  of  the  arm. 
What  is  a,  joint? 

Describe  a  joint  like  that  at  the  elbow. 
Describe  a  joint  like  those  between  the  bones  of  the  back- 
bone. 

Describe  a  joint  like  those  between  the  skull  bones. 
What  is  a,  ligament  ? 

What  happens  to  ligaments  when  a  joint  is  sprained  ? 
What  should  you  do  for  a  sprained  joint  ? 


BONES   AND   JOINTS  75 

What  should  you  do  for  a  bone  that  is  out  of  joint  ? 

How  can  you  show  that  a  bone  is  composed  of  both  flesh  and 
mineral  matter  ? 

What  is  cartilage? 

What  is  a  common  cause  of  deformed  bones  ? 

What  is  a  common  cause  of  bone  diseases  ? 

How  is  a  broken  bone  repaired  ? 

Why  do  the  bones  of  a  child  not  become  broken  so  easily  as 
those  of  a  grown  man  ? 

What  should  you  do  for  a  person  who  has  a  broken  bone  ? 


CHAPTER  VIII 
MUSCLES 

Involuntary  Muscles.  —  Nearly  all  movements  in 
the  body  are  produced  by  groups  of  cells  called  muscles. 
The  movements  are  of  two  kinds.  One  kind  is  that 
which  the  mind  cannot  control,  such  as  the  flow  of 
blood  through  the  body,  and  the  passage  of  food  through 
the  organs  of  digestion.  The  muscles  which  produce 
these  movements  are  called  involuntary  muscles. 

Involuntary  muscles  are  almost  white,  or  colorless. 
Most  of  them  are  in  the  form  of  thin  sheets  surrounding 
the  blood  tubes,  and  the  tubes  in  which  food  is  digested. 
They  are  composed  of  cells  which  are  thick  in  the  middle 
and  taper  toward  their  ends.  When  the  cells  act,  they 
make  themselves  thicker  and  shorter.  In  this  way 
they  lessen  the  size  of  the  tube  which  they  surround, 
and  produce  motion  in  anything  which  the  tube  may 
contain. 

Voluntary  Muscles.  —  A  second  kind  of  motion  in 
the  body  is  that  which  is  under,  the  control  of  the  mind, 
such  as  the  movements  of  the  arms,  legs,  and  head. 
The  cells  which  produce  these  movements  are  called 
voluntary  muscles.  By  the  word  muscle  we  usually 
mean  a  voluntary  muscle. 

76 


MUSCLES 


77 


The  muscles  of  the  body  of  an  animal  are  its  lean 
meat.  The  muscles  of  a  person  are  like  the  lean  meat 
of  a  lower  animal,  and  form  about  half  of  the  weight  of 
the  body.  The  most  of  them  surround  the  bones,  and 
lie  just  beneath  the  skin. 

There  are  about  four  hundred  separate  muscles  in  the 
body,  each  of  which  has  a  name.  The  muscle  which  lies 
on  the  front  side  of  the 
arm  above  the  elbow  is 
called  the  biceps  muscle. 
Its  use  is  to  bend  the 
elbow.  The  muscle  which 
lies  on  the  back  side  of 
the  upper  arm  straightens 
the  elbow,  and  is  called 
the  triceps  muscle. 

Examination  of  a  Mus- 
cle.—  You  can  see  what 
your  own  muscles  are  like 
by  looking  at  the  meat  in 
a  butcher's  shop,  for  the 
muscles  of  the  common 
lower  animals  are  nearly 
the  same  in  number  and 
arrangement  as  the  mus- 
cles of  your  own  body.  A  Muscles  and  tendons  on  the  front  of 
leg  Of  lamb  Consists  of  the  foreleg  of  a  cat. 

bundles  of  musc'es  surrounding  the  leg  bones.     Each 
muscle  is  large  at  its  upper  end,  and  tapers  toward  its 


MUSCLES 


lower  end,  where  it  ends  in  a  strong  white  connective 
tissue  cord  called  a  tendon.  The  tendon  is  fastened 
to  a  bone  in  the  lower  part  of  the  leg. 

How  a  Muscle  Acts.  —  When  a  muscle  acts,  it  makes 
itself  hard  and  firm,  and  becomes  larger  around  and 
shorter  than  when  it  is  at  rest.  In  this  way  it  draws 
its  ends  toward  its  middle  part,  and  causes  its  tendon  to 
pull  upon  whatever  is  fast  to  it.  The  shortening  and 

hardening  of  a  muscle 
is  called  its  contraction. 
Nearly  all  the  mus- 
cles of  the  arms  and 
legs  are  arranged  like 
the  muscles  in  a  leg  of 
lamb.  The  upper  end 


Muscles  and  tendons  on  the  back  of  the 
hind  leg  of  a  cat. 


of  each  muscle  is  fas- 
tened to  a  bone,  either 
in  the  trunk,  or  in  the 
upper  part  of  a  limb. 
The  tendon  at  its  lower  end  is  fastened  to  another  bone 
after  crossing  the  joint.  Each  muscle  usually  connects 
two  bones,  and  its  action  is  to  make  the  lower  bone 
move  at  the  joint  like  a  door  on  its  hinges.  Nearly  all 
voluntary  motions  of  the  body  are  the  bending  of  joints. 
You  can  see  how  a  muscle  acts  by  examining  your 
own  arm.  Bend  your  elbow  as  far  and  as  strongly  as 
you  can,  and  feel  the  biceps  muscle  swell  in  a  hard 
bunch.  Feel  in  the  bent  side  of  the  elbow  for  the  ten- 
don as  it  pulls  upon  the  forearm. 


MUSCLES 


79 


Face  Muscles.  —  Many  of  the  muscles  of  the  face 
are  fastened  to  the  skin.  When  they  contract,  they 
move  the  lips  and  cheeks,  wink  the  eyelids,  and  wrinkle 
the  skin.  The  motions  of  the  face  often  show  how  a 
person  feels.  If  he  is  happy,  his  muscles  will  pull  the 
corners  of  his  mouth  upward  and  backward  in  a  smile. 
If  he  feels  sad  or  is  in  pain,  other  muscles  will  pull  the 
corners  of  his  mouth  downward,  as  in  crying.  If  he  is 
angry,  the  muscles  will  wrinkle  his  forehead  in  a  scowl. 

The  face  muscles  which  you  often  use  will  produce 
marks  and  wrinkles  on  the  skin,  and  will  show  a  great 
deal  about  your  character  and  disposition.  If  you 
smile  often,  you  will  carry  the  marks 
of  the  smile  through  life.  If  you 
are  often  angry,  you  will  carry  a 
scowl  upon  your  forehead.  If  you 
practice  kindness  and  gentleness 
while  you  are  young,  you  will  carry 
their  signs  on  your  face  all  through 
life. 

Structure  of  Muscle.  —  A  volun- 
tary muscle  is  composed  of  cells 
about  the  size  and  shape  of  short 
fibers  of  cotton.  If  you  look  at 
muscle  cells  under  a  microscope,  you 
can  see  faint  lines  running  across 
them.  The  cells  lie  side  by  side, 
and  are  held  in  their  places  by  fine  branches  of  con- 
nective tissue  cells.  Muscle  cells  are  soft  like  jelly, 


Muscle  cells. 
fied. 


Magni- 


8o 


MUSCLES 


but  the  connective  tissue 
cells  around  them  are  almost 
as  tough  as  fibers  of  cotton. 
The  toughness  of  meat  is 
due  to  the  connective  tissue 
in  it. 

The  special  work  of  muscle 
cells  is  to  shorten  themselves 
in  order  to  produce  motion 
in  some  other  part  of  the 
body.  There  is  a  slight  mo- 
tion among  the  particles  of 

Muscle  cells  cut  across.    Mag-    every  living  cell,  but  a  mus- 
cle cell  can   move  so  much 

that  it  produces  motions  in  other  parts  of  the  body. 
A  tendon  is  composed  of  connective  tissue  fibers 

which    are    fastened    to    the 

connective      tissue      of      the 

muscle. 

Strength    of    Muscle.  —  A 

muscle  one  inch  in  diameter 

can    lift    about    seventy-five 

pounds.      Frogs    and    grass- 
hoppers   seem    to    be    much 

stronger  than  a  man  of  the 

same  size  would  be,  but  this 

is  only  because  their  bodies 

are  lighter.     Their  muscle  is 

only  half  as  strong  as  a  bit 


Connective  tissue  at  the  end  of 
a  tendon. 


MUSCLES  8 1 

of  man's  muscle  which  is  of  the  same  size  as 
theirs. 

It  would  be  a  simple  problem  in  arithmetic  to  reckon 
the  strength  of  one  of  your  muscles.  Feel  of  your 
biceps  muscle,  measure  its  diameter,  and  find  out  how 
many  bundles  one  inch  in  diameter  would  be  needed 
to  make  a  bundle  as  large  around  as  your  muscle. 
From  this  you  can  tell  how  many  pounds  your  muscle 
can  lift  by  a  direct  pull. 

Source  of  Muscular  Strength.  —  A  fine  network  of 
blood  tubes  surrounds  each  muscle  cell.  The  blood 
which  flows  through  the  tubes  brings  both  food  and 
oxygen  to  the  cells.  When  a  muscle  contracts,  it  takes 
some  of  the  oxygen  and  oxidizes  either  some  of  the  food, 
or  some  of  its  own  substance  (p.  31).  The  oxida- 
tion supplies  the  power  and  strength  which  the  muscle 
puts  forth  in  its  work. 

The  contraction  of  a  muscle  may  take  place  in  an 
instant,  like  the  uncoiling  of  a  spring  suddenly  re- 
leased, or  the  muscle  may  contract  slowly,  like  a  spring 
pulling  steadily.  A  contraction  is  started  by  an  order 
which  the  brain  sends  to  the  muscles  by  means  of  a 
nerve. 

Muscle  Growth.  —  Using  the  muscles  is  called  ex- 
ercise. A  muscle  at  rest  takes  very  little  food  and 
oxygen  from  the  blood.  If  muscles  are  not  used,  they 
soon  become  small  and  weak,  but  when  they  work, 
they  use  up  a  great  deal  of  food  and  oxygen,  and  take 
in  a  large  supply  from  the  blood.  Muscle  cells  are 

GEN.    HYG. 6 


82  MUSCLES 

living  things,  and  when  they  are  often  called  upon  to 
do  work,  they  prepare  themselves  for  it  by  storing 
up  a  supply  of  food  in  their  own  substance.  For  this 
reason  exercise  makes  the  muscles  grow  large  and 
strong. 

Many  young  persons  take  exercise  to  make  their 
bodies  grow  shapely  and  beautiful.  They  go  to  gym- 
nasiums to  have  the  size  of  the  muscles  measured,  and 
their  strength  tested,  and  to  have  the  instructors  tell 
them  what  exercises  will  increase  their  size  and  strength. 
If  their  upper  arms  are  small,  they  take  exercises  which 
require  the  arms  to  be  moved  at  the  elbow,  and  in  this 
way  they  increase  the  size  of  their  biceps  and  triceps 
muscles.  A  young  person  can  develop  any  part  of 
the  body  by  exercising  it. 

Turning  your  ankles  when  you  stand  or  walk  is  due 
to  a  weakness  of  the  muscles  of  your  legs.  You  can 
strengthen  those  muscles  and  make  your  ankles  strong 
by  practicing  standing  on  tiptoe,  or  by  taking  walks 
uphill. 

Round  Shoulders.  —  The  principal  support  of  the 
arms  and  shoulders  are  the  muscles  on  the  back  side 
of  the  neck  and  trunk.  If  the  muscles  are  weak,  the 
shoulders  fall  forward,  producing  round  or  stooped 
shoulders.  The  straight  back  and  full  chest  of  a 
soldier  are  due  to  training  the  muscles  which  hold  the 
shoulders  up.  You  can  exercise  the  muscles  of  your 
back  by  always  holding  your  shoulders  up  when  you 
sit  or  stand.  In  a  little  while  your  muscles  will  grow 


MUSCLES  83 

so  strong  that  they  will  support  your  shoulders  with- 
out your  thinking  about  their  action. 

Exercise  and  Endurance.  —  Exercise  trains  the  mus- 
cles to  work  for  hours  at  a  time,  and  to  endure  hard 
labor  without  tiring.  Athletes  and  circus  actors  have 
to  take  exercise  every  day  in  order  that  their  muscles 
may  endure  their  work.  If  they  should  stop  exercising 
for  a  few  days,  their  muscles  would  become  tired  soon 
after  they  begin  to  do  their  acts. 

Every  person  has  to  make  some  use  of  his  muscles. 
Even  writing  at  a  desk  requires  muscular  work  to  hold 
the  body  upright,  and  is  extremely  tiresome  to  those 
whose  muscles  are  weak.  Many  scholars  fail  in  their 
work  because  they  do  not  cultivate  enough  muscular 
strength  to  enable  them  to  sit  at  their  desks  all  day. 
Riding  in  an  automobile  or  in  a  railroad  train  requires 
an  amount  of  muscular  work  which  often  tires  a  strong 
man.  You  cannot  have  strength  and  endurance  to 
carry  on  your  daily  work  unless  you  take  exercise  every 
day. 

Exercise  and  Health.  —  One  of  the  greatest  of  all 
reasons  for  taking  exercise  is  to  keep  the  whole  body  in 
good  order.  Muscles  use  up  the  greater  part  of  the 
food  and  air  which  enter  the  body.  If  they  are  in  good 
order,  the  digestive  organs  try  to  supply  them  with  a 
large  quantity  of  food,  the  lungs  take  in  a  large  amount 
of  air  for  their  use,  and  the  heart  sends  the  blood  flowing 
swiftly  to  carry  them  what  they  need.  The  whole  body 
receives  benefit  from  exercise  of  the  muscles. 


84  MUSCLES 

When  you  do  not  use  your  muscles,  you  have  very 
little  need  of  food.  You  do  not  have  much  appetite, 
and  your  stomach  digests  only  a  little  food.  You  also 
have  very  little  use  for  oxygen,  and  you  breathe  lightly. 
All  the  actions  in  your  body  are  lessened,  and  you  feel 
dull  and  weak  all  over.  You  must  take  exercise  if 
you  would  keep  your  body  well  and  strong. 

Kind  of  Exercise.  —  While  you  sit  at  a  desk  all  day, 
you  use  your  muscles  in  a  gentle  way  which  finally  tires 
them,  but  the  work  which  they  do  does  not  require 
you  to  breathe  deeply,  or  your  heart  to  beat  hard. 
The  kind  of  exercise  which  helps  you  is  that  which 
makes  you  breathe  deeply,  sends  the  blood  to  your  face, 
and  warms  your  whole  body.  Every  man,  woman,  and 
child  needs  at  least  an  hour  of  this  kind  of  exercise  every 
day.  Scholars  at  school  cannot  have  clear  minds 
unless  they  take  at  least  this  amount  of  exercise. 

If  you  have  to  work  with  your  hands,  you  will  get 
exercise  while  you  work.  Farmers,  carpenters,  errand 
boys,  and  house  maids,  all  get  exercise  while  they  do 
their  work.  But  students  and  bookkeepers  often 
have  very  little  muscular  work  to  do,  and  they  may  get 
exercise  by  walking,  bicycling,  rowing,  fishing,  playing 
outdoor  games,  and  taking  part  in  athletic  sports. 

One  of  the  best  ways  of  taking  exercise  is  to  become 
interested  in  some  kind  of  active  work  or  sport.  Fads 
and  sports,  such  as  photography,  gardening,  and  fish- 
ing, have  often  been  the  means  of  leading  sickly  persons 
to  take  needed  exercise,  and  of  restoring  them  to  health. 


MUSCLES  85 

Muscles  need  pure,  fresh  air  as  much  as  they  need 
good  food.  The  best  exercise  is  that  which  is  taken  out 
of  doors  where  the  air  is  pure  and  free  from  dust. 

Gymnasiums  and  Playgrounds.  —  Children  in  large 
cities  often  have  no  work  to  do,  and  no  place  to 
play.  It  is  the  duty  of  those  who  have  them  in  charge 
to  provide  the  means  and  the  places  for  their  exercise. 
It  is  a  good  investment  for  taxpayers  to  give  their 
money  for  gymnasiums,  playgrounds,  and  parks,  where 
children  can  play  and  develop  strong,  healthy  bodies. 

Alcohol  and  Muscular  Strength.  —  Many  experi- 
ments have  been  made  to  find  out  whether  or  not  the  use 
of  an  alcoholic  drink  will  increase  a  person's  strength. 
These  experiments  have  always  proved  that  alcohol 
lessens  the  strength  instead  of  increasing  it.  Athletes 
in  training  are  not  allowed  to  drink  any  form  of  alcoholic 
liquor  at  all. 

Alcohol  and  Endurance.  —  Experiments  have  been 
made  to  find  out  whether  or  not  alcohol  will  help  a  person 
to  put  his  muscles  to  hard  use  for  hours  at  a  time.  They 
prove  that  alcohol  lessens  the  endurance.  No  civilized 
nation  now  supplies  alcoholic  drinks  to  its  soldiers  and 
sailors  as  was  formerly  done,  for  on  long  marches  and 
in  severe  hardships  those  who  drink  are  the  first  to  fail 
in  strength.  No  explorer  in  deserts  and  arctic  lands 
will  allow  his  men  to  use  strong  drink. 

Alcohol  and  Accuracy  of  Motion.  —  Experiments 
have  been  made  to  find  out  whether  or  not  alcoholic 
drinks  will  help  a  person  to  do  quick  and  accurate 


86  MUSCLES 

work  with  his  muscles,  such  as  setting  type  or  shooting 
at  a  mark.  It  is  proved  that  alcohol  always  lessens 
the  speed  and  accuracy  of  the  worker.  But  very  often 
it  deceives  a  person  and  makes  him  believe  that  he  is 
doing  his  work  more  quickly  and  accurately.  • 

Tobacco  and  Muscles.  --The  nicotine  of  tobacco  is 
a  poison  to  the  muscles.  Tobacco  cannot  increase  the 
strength.  Soldiers,  sailors,  and  explorers  sometimes 
say  that  tobacco  helps  them  to  do  their  work.  They 
do  not  use  tobacco  to  increase  their  strength,  but  to 
help  themselves  to  be  contented  and  to  rest  after  doing 
hard  work.  If  tobacco  were  of  any  value  in  helping 
tired  persons  to  rest,  it  would  be  used  in  sickness. 
But  those  who  smoke  or  chew  do  not  care  to  do  so  when 
they  are  sick,  for  they  then  feel  the  poisonous  effects 
of  the  nicotine  just  as  if  they  had  never  used  tobacco. 

Tobacco  is  more  poisonous  to  the  muscles  of  a  young 
man  than  to  those  of  a  grown  person.  A  boy  who 
smokes  cigarettes  cannot  become  a  good  athlete,  nor 
endure  hard  work.  The  use  of  cigarettes  will  spoil  a 
boy's  reputation  as  a  worker,  and  those  who  wish  to 
employ  bright,  active  boys  will  not  take  cigarette 
smokers  if  they  can  help  it. 

QUESTIONS 

What  is  the  difference  between  an  involuntary  muscle  and 
a  voluntary  one  ? 

Where  may  involuntary  muscles  be  found  ? 

How  much  of  the  body  is  composed  of  voluntary  muscles  ? 


MUSCLES  87 

How  many  muscles  are  in  the  body  ? 

Where  is  the  biceps  muscle  ? 

Where  is  the  triceps  muscle  ? 

What  is  a  tendon  ? 

What  change  takes  place  in  the  shape  of  a  muscle  when  it 
starts  to  act  ? 

To  what  are  the  muscles  of  the  arms  and  legs  fastened  ? 

When  a  muscle  acts,  what  does  it  do  to  a  bone  or  joint  ? 

How  do  the  muscles  of  the  face  produce  a  smile  ? 

What  is  the  shape  of  a  muscle  cell  ? 

What  is  the  use  of  connective  tissue  between  the  cells  ? 

How  many  pounds  can  be  lifted  by  a  muscle  one  inch  in 
diameter  ? 

How  could  you  reckon  how  much  your  biceps  muscle  can 
lift? 

From  what  does  a  muscle  get  its  power  to  act  ? 

What  makes  you  feel  warm  when  you  work  hard  with  your 
muscles  ? 

What  causes  muscles  to  act  ? 

What  is  exercise  ? 

What  are  some  of  the  benefits  which  you  may  get  from  taking 
exercise  ? 

If  your  arms  are  small,  how  may  you  increase  their  size  ? 

If  you  become  tired  out  after  walking  a  few  blocks,  how  can 
you  increase  the  endurance  of  your  muscles  ? 

How  does  exercising  your  muscles  help  your  lungs  ? 

Name  some  good  kinds  of  exercise. 

Give  a  reason  why  the  people  of  a  city  should  vote  money  to 
pay  for  gymnasiums  and  playgrounds. 

What  effect  does  alcohol  have  upon  muscular  strength? 
upon  endurance  ?  upon  accuracy  of  movements  ? 

What  effect  does  tobacco  have  upon  the  muscles  ? 


CHAPTER  IX 
CIRCULATION  OF  BLOOD 

Use  of  Blood.  —  The  cells  of  the  body  eat,  breathe, 
and  grow,  like  separate  microscopic  animals  outside  of 
the  body.  They  cannot  go  in  search  of  food  and 
oxygen,  but  everything  which  they  need  is  brought  to 
them  by  a  red  liquid  that  is  always  flowing  through 
every  part  of  the  body.  This  liquid  is  the  blood.  The 
blood  also  takes  away  the  waste  matters  which  the 
cells  give  off,  and  it  protects  the  cells  from  disease 
germs  which  may  enter  the  flesh.  The  life  of  the  body 
depends  upon  the  blood. 

Composition  of  Blood.  —  Blood  consists  of  a  clear, 
yellow  liquid  called  plasma,  or  serum,  which  is  full  of 
cells  called  blood  cells,  or  corpuscles.  About  one  half 
of  the  blood  is  plasma,  and  the  other  half  is  blood  cells 
which  float  in  the  plasma. 

Plasma.  —  The  plasma  of  the  blood  consists  of  water 
containing  protein,  fat,  sugar,  and  minerals,  all  of 
which  are  to  become  food  for  the  cells  of  the  body.  It 
also  contains  small  quantities  of  waste  matters  which  it 
has  washed  away  from  the  cells. 

Clot.  —  After  blood  flows  from  the  body,  it  becomes 
solid,  like  jelly.  Blood  in  a  solid  form  is  called  a  clot. 


CIRCULATION  OF  BLOOD 


89 


The  effect  of  clotting 

is   to   form   a   solid 

mass  which  will  stop 

the  bleeding  in  a  cut 

or  wound. 
Red  Blood  Cells. 
-  Most  of  the  cells 

which   float   in   the 

blood  are  red,  and 

give  the  red  color  to 

the     blood.       They 

may  easily  be  seen 

by  examining  a  thin  Red  blood  cells- 

smear  of  blood  with  a  microscope.     A  red  blood  cell  is 

shaped  like  a  thick  round  plate  with  a  hollow  on  each 

side. 

The  use  of  the  red  blood  cells  is  to  carry  oxygen  from 

the  lungs  through 
the  body.  They 
do  this  by  means 
of  their  red  color- 
ing matter,  called 
hemoglobin,  which 
contains  iron. 
Every  cell  which 
touches  the  air  on 
the  outside  of  the 
body  takes  oxygen 

Red  blood  cells  in  piles.  for     its     Own     USCJ 


CIRCULATION   OF   BLOOD 


| 


White  blood  cells. 


but  red  blood  cells  take  far  more  oxygen  than  they 
themselves  need,  and  they  carry  it  to  the  cells  which 

lie  deep  in  the  body  and  cannot 
get  it  for  themselves. 

White  Blood  Cells.  —  Some 
of  the  blood  cells  are  round  like 
balls,  and  are  almost  colorless, 
but  when  many  of  them  are 
seen  together  they  appear 
white.  These  are  called  white 
blood  cells,  or  white  corpuscles.  One  of  their  uses  is 
to  destroy  bacteria  and  other  disease  germs  which 
may  have  entered  the  body.  We  can  see  white  blood 
cells  by  looking  at  the  white 
matter  from  a  pimple  with 
a  microscope.  This  matter 
consists  of  white  blood  cells 
which  bacteria  in  the  pimple 
have  destroyed. 

Arteries.  -  -  The  blood  in 
the  body  is  held  in  tubes, 
and  is  kept  in  motion  by  a 
pump  called  the  heart.  The 
heart  sends  blood  to  every 
part  of  the  body  by  means 
of  a  set  of  tubes  called  ar- 
teries. All  the  arteries,  except  those  in  the  lungs,  are 
branches  of  a  single  artery  which  begins  at  the 
heart,  and  is  called  the  aorta.  The  larger  arteries 


A   small   artery   cut    crosswise. 
Magnified. 


CIRCULATION   OF   BLOOD  91 

lie  deep  in  the  flesh  where  they  cannot  be  easily 
harmed. 

The  larger  arteries  in  the  body  have  been  given 
names.  For  example,  the  one  on  the  thumb  side  of 
the  wrist  is  called  the  radial  artery. 

Muscles  of  the  Arteries.  --The  arteries  are  elastic, 
like  rubber  tubes.  Their  walls  consist  largely  of  in- 
voluntary muscle  cells  which  may  contract  or  relax, 
and  make  the  tube  small  or  large,  according  to  the 
needs  of  the  various  parts  of  the  body  (p.  76).  When 
any  part,  such  as  an  arm,  is  put  to  hard  use,  its  arteries 
become  large  in  order  to  supply  a  large  amount  of 
blood  to  it.  When  a  person  is  too  warm  from  running, 
his  face  is  red,  because  the  arteries  become  large  in 
order  to  allow  a  large  amount  of  blood  to  flow  near  the 
air  and  become  cooled. 

The  contraction  of  arteries  may  be  seen  in  an  earth- 
worm. A  large  blood  tube  runs  along  its  back  and 
another  along  its  under  side.  By  watching  a  tube 
closely  you  can  see  it  contract  regularly  about  once 
every  four  seconds.  The  earthworm  has  no  heart,  but 
the  regular  contractions  of  the  blood  tubes  keep  the 
blood  in  motion. 

Veins.  -  -  The  blood  is  returned  to  the  heart  by  means 
of  a  set  of  tubes  called  veins.  The  veins  are  like  the 
arteries,  except  that  in  them  the*  blood  flows  from  the 
small  branches  into  the  large  trunks.  These  large 
trunks  open  into  the  heart.  We  can  see  veins  on  the 
back  of  the  hand  by  holding  the  hand  down  at  arm's 


CIRCULATION   OF   BLOOD 


length  for  a  moment.     The  blood  will  fill  the  veins,  and 
will  make  them  look  like  bluish  ridges  on  the  skin. 

The  larger  veins  in  the  body  have  been  given  names. 
For  example,  the  principal  vein  on  the  side  of  the  neck 
is  called  the  jugular  vein. 

Valves  of  the  Veins.  —  Veins  contain  valves  which 
open  toward  the  heart.  When  a  muscle  contracts,  it 
squeezes  blood  from  its  veins.  The  blood  must  flow 
onward,  for  the  valves  prevent  it  from  flowing  back- 
ward. Thus  exercise  helps  the  flow  of  blood  through 
the  body. 

If  a  person  is  weak  and  sick,  the  heart  may  not  be 
strong  enough  to  force  the  blood  rapidly  through  the 
veins  of  the  arms  and  legs.  Rubbing  the  limbs  toward 
the  body  will  help  the  flow  of  blood,  and  be  refreshing 

to   the   sick   person. 
Proof  of  the  Flow  of  Blood. 
-  The  movements  of  the  blood 
were  not  known  until  an  Eng- 
lish physician,  named  William 
Harvey,  discovered  them  about 
1628.     You  can  easily  perform 
one  of  his  experiments  to  prove 
how  the  blood  flows. 

Press  a  finger  upon  a  vein  on 

4  the  back  of  the  hand,  and  rub 

another  finger  from  it  toward 
the  heart  in  order  to  empty  the 
vein  of  blood.  Lift  the  second 


Veins  on  the  hand,  full. 


CIRCULATION   OF   BLOOD 


93 


finger  and  blood  will  return  and  fill  the  upper  part  of 

the  vein  down  to  a  set  of  valves,  but  the  lower  part 

of  the  vein  will  remain 

empty.     Now  lift  the 

lower  finger,  and  blood 

at  once  fills  the  whole 

vein.    This  experiment 

shows  the  direction  of 

the   flow   of   blood   in 

the  veins  of  the  hand. 

Capillaries.  —  Blood 
goes  from  the  smallest 
branches  of  the  arter- 
ies into  the  smallest 
branches  of  the  veins 
by  passing  through  a 
set  of  fine  tubes  called 
capillaries.  The  capil- 
laries extend  around 
and  between  the  cells 

of  the  body  in  a  network  so  fine  that  every  cell  touches 
one  or  more  of  the  tubes.  Capillaries  are  so  small 
that  the  separate  ones  cannot  be  seen  without  a  micro- 
scope. They  are  so  numerous  and  so  close  together 
that  they  make  the  skin  look  as  if  it  were  painted  pink. 
Pressing  a  finger  on  the  skin  will  force  the  blood  from 
the  capillaries,  and  when  the  finger  is  lifted,  it  will 
leave  a  white  spot  for  a  moment  until  the  blood  fills  the 
capillaries  again. 


Experiment  to  show   the  action  of   the 
valves  in  the  veins. 


94 


CIRCULATION   OF   BLOOD 


Capillaries  around  muscle  cells. 


A  fish  arranged  under  a  microscope 
to  show  the  circulation  of  blood. 


The  walls  of  the  capil- 
laries are  so  thin  that 
some  of  the  plasma  and 
oxygen  from  the  blood 
easily  soak  through  them 
and  stay  behind  for  the 
use  of  the  cells,  while  the 
rest  of  the  blood  passes 
into  the  veins.  At  the 
same  time,  carbonic  acid 
and  other  waste  mat- 
ters from  the  cells  pass 
into  the  blood  stream 
and  flow  away  through 
the  veins.  Thus  the  cap- 
illaries distribute  food 


CIRCULATION  OF   BLOOD 


95 


and  oxygen  to  the  cells  and 
take  away  their  waste  mat- 
ters. 

Seeing  Capillaries.  --  You 
may  see  the  flow  of  blood 
through  the  capillaries  by 
using  a  microscope  and  ex- 
amining the  tail  of  a  very 
small  fish,  or  the  web  of  a 
frog's  foot,  or  the  thin  sheet 
of  tissue,  called  the  mesen- 
tery, which  holds  the  frog's 
intestine  in  place.  The  blood 
pear  like  orange-colored  balls 


Heart  of  a  lamb. 


Capillaries  in  a  frog's  foot. 

cells  in  a  capillary  ap- 
tumbling  over  and  over 
as  the  blood  carries 
them  along.  A  cap- 
illary is  usually  of 
such  size  that  it  al- 
lows from  two  to 
four  red  blood  cells 
to  pass  through  side 
by  side. 

The  Heart.— The 
heart  is  made  of  firm 
muscle,  and  is  about 
the  size  and  shape  of 
a  person's  fist.  Its 
smaller  end  may  be 
felt  throbbing  under 


CIRCULATION  OF   BLOOD 


the  skin  a  little  to  the  left  of  the  lower  end  of  the 
breastbone.  It  is  hollow,  and  is  divided  into  four 
compartments,  two  of  which  are  called  auricles,  and 
two  are  called  ventricles.  Each  auricle  receives  blood 

from  the  veins,  and 
each  ventricle 
sends  blood  into  an 
artery. 

How  the  Heart 
Pumps  Blood.  - 
The  ventricles 
have  thick  walls  of 
muscle  which  form 
the  greater  part  of 
the  heart.  Each 
ventricle  has  a 
door,  or  valve, 
opening  inward 
from  the  auricle, 
and  another  valve 
opening  outward 
at  the  beginning 
of  the  artery.  A  ventricle  receives  blood  from  its 
auricle,  and  when  it  is  full,  it  suddenly  contracts  and 
becomes  smaller,  thus  forcing  the  blood  out.  The 
valve  at  the  auricle  does  not  allow  the  blood  to  flow 
backward  into  the  auricle,  but  the  valve  which  opens 
outward  allows  it  to  flow  into  the  artery. 

After  the  ventricle  has  emptied  itself,  its  muscles 


The  valves  between  an  auricle  and  a  ventricle. 


CIRCULATION   OF   BLOOD 


97 


relax  and  allow  more  blood  to  enter  from  the  auricle, 
but  the  valve  at  the  artery  closes  and  does  not  allow 
the  blood  to  flow  backward  from  the  artery.  In  this 
manner  the  ventricles 
keep  the  blood  flowing 
through  the  arteries 
away  from  the  heart. 

Pulse.  --  The  heart 
of  a  grown  person  con- 
tracts or  beats  about 
seventy  times  each 
minute,  and  each  beat 
sends  about  four  table- 
spoonfuls  Of  blood  into  The  valve  whkh  prevents  blood  from  flow- 
the  arteries.  The  inS  f rom  the  main  artery  back  into  the 

blood    flows    through 

the  arteries  in  spurts  or  waves  called  the  pulse  beats. 
You  can  feel  the  pulse  when  you  press  lightly  upon  the 
flesh  over  a  large  artery.  By  feeling  the  pulse  you 
can  tell  how  fast  and  how  strongly  the  heart  is  beat- 
ing. One  of  the  best  places  to  feel  the  pulse  is  in  the 
radial  artery  on  the  front  of  the  wrist  (p.  91). 

Venous  and  Arterial  Blood.  —  Blood  which  is  full  of 
oxygen  is  bright  red  in  color,  but  it  becomes  dark  red  of 
purple  when  it  loses  the  oxygen.  Blood  in  the  arteries 
is  bright  red,  for  it  is  then  carrying  a  large  quantity 
of  oxygen  to  the  cells  of  the  body.  It  loses  its  oxygen 
in  passing  through  the  capillaries,  and  so 'its  color  is 
purple  in  the  veins.  You  can  see  the  difference  in 

GEN.    HYG. 7 


98 


CIRCULATION  OF  BLOOD 


color  between  arterial  and  venous  blood  by  looking 
at  the  veins  in  the  back  of  a  person's  hand.  The  skin 
is  colored  pink  by  the  arterial  blood  in  the  capillaries, 

but  the  blood  in 
the  veins  is  bluish, 
for  it  contains  but 
little  oxygen. 

Circulation  of 
Blood,  —  The  flow 
of  blood  through 
the  body  is  called 
the  circulation. 
The  venous  blood 
which  comes  back 
to  the  heart  con- 
tains but  little  oxy- 
gen, and  is  full  of 
carbon  dioxide 
which  it  has  taken 
from  the  cells. 
Before  it  is  sent 
through  the  body 
again,  it  is  sent  to 

Diagram  of  the  circulation  of  blood.  j-^e  lungS  to  get  rid 

of  the  carbon  dioxide  and  to  get  a  load  of  oxygen. 
The  heart  is  a  double  pump.  Its  right  ventricle 
pumps  blood  to  the  lungs,  and  its  left  ventricle  pumps 
it  to  all  the  body.  Even  the  tissues  of  the  lungs 
receive  blood  from  the  left  ventricle. 


CIRCULATION   OF   BLOOD  99 

A  drop  of  blood  will  go  the  full  rounds  of  the  circula- 
tion in  about  two  minutes.  In  doing  so  it  will  pass 
through  the  following  structures  :  - 

1.  Left  ventricle  6.    Right  ventricle 

2.  Arteries  of  all  parts  of     7.    Artery  to  the  lungs 

the  body  8.    Capillaries  of  the  lungs 

3.  Capillaries  9.   Veins  to  the  heart 

4.  Veins  10.   Left  auricle 

5.  Right  auricle  n.   Left  ventricle  again 
Lymph.  -  -  The  plasma  which  passes  through  the  sides 

of  the  capillaries  and  goes  to  the  cells  is  called  lymph. 
It  surrounds  the  cells  of  the  body  and  fills  all  spaces 
among  the  tissues,  like  water  in  a  sponge.  The  cells 
of  the  flesh  lie  in  the  lymph  like  fishes  in  water.  They 
take  their  food  and  oxygen  from  the  lymph  and  give 
off  their  waste  matters  to  it.  The  liquid  which  stands 
on  the  raw  flesh  after  a  bit  of  skin  has  been  knocked 
from  the  knuckles  is  lymph. 

The  Flow  of  Lymph.  —  The  lymph  in  the  flesh  is 
slowly  returned  to  the  blood  in  the  veins  near  the  heart 
by  a  set  of  tubes  called  lymphatics.  These  tubes  are 
so  small  and  thin  that  they  can  scarcely  be  seen.  They 
are  arranged  like  the  veins,  and  contain  valves  which 
allow  the  lymph  to  flow  only  toward  the  veins.  When 
the  muscles  contract,  they  press  upon  the  lymphatics 
and  force  the  lymph  out  of  the  flesh,  and  into  the  veins. 
Thus  muscular  exercise  helps  the  flow  of  the  liquid  which 
nourishes  and  cleanses  the  cells. 

Rubbing  the  limbs  toward  the  body  is  refreshing  to 


ioo  CIRCULATION   OF   BLOOD 

a  sick  person,  for  it  makes  the  lymph  flow  back  to  the 
veins,  and  thus  removes  the  waste  matters  from  the 
tissues.  The  rubbing  also  helps  the  flow  of  blood 
through  the  veins  (p.  92). 

Circulation  and  Water  Supply  Compared.  —  The 
circulation  of  blood  in  the  body  is  like  the  water  supply 
of  a  city.  The  heart  is  like  the  pumping  station. 

The  arteries  are  like  the  pipes  which  lead  from  the 
pumping  station,  and  send  branches  to  the  faucets  in 
the  houses. 

The  flow  of  blood  in  the  capillaries  is  like  the  flow  of 
water  from  the  faucets.  The  use  of  the  arteries  is  to 
carry  blood  to  the  capillaries,  just  as  the  use  of  the 
water  pipes  is  to  carry  water  to  the  faucets. 

The  veins  are  like  the  waste  pipes  and  sewers  which 
carry  the  waste  water  from  the  houses.  A  difference 
between  them  is  that  the  veins  return  the  blood  to  the 
heart  to  be  pumped  over  again,  while  the  sewers  empty 
the  waste  water  at  a  distance  from  the  pumping  station. 

Lymph  is  like  water  which  has  been  drawn  from  a 
faucet,  and  is  taken  away  to  be  used  in  cooking  or 
washing.  After  lymph  has  been  used,  it  is  returned  to 
the  veins,  just  as  the  water  which  has  been  taken 
away  from  the  faucets  is  finally  poured  into  the  sewers. 

Heart  and  Exercise.  —  Cells  have  use  for  much  more 
blood  while  they  are  at  work  than  while  they  are  at  rest. 
The  heart  is  like  a  water  pump  that  regulates  itself. 
When  a  person  takes  exercise,  his  heart  beats  strongly 
and  rapidly  in  order  to  send  a  large  amount  of  blood 


CIRCULATION   OF  BLQOD-  /',  ;v'^    IO1 

to  the  muscles.  Count  your  pulse  while  you  are  sitting 
quietly  in  your  seat,  and  you  will  find  it  beating  about 
seventy  or  eighty  times  a  minute.  Then  run  up  and 
down  stairs  or  around  the  schoolhouse,  and  count  your 
pulse  again.  It  will  now  beat  over  a  hundred  times  a 
minute,  and  may  be  felt  much  more  readily  than  while 
you  were  sitting  still. 

Exercise  will  strengthen  the  heart,  as  it  will  any 
other  muscle  in  your  body.  But  there  is  danger  in 
taking  too  much  exercise,  for  it  may  cause  your  heart 
to  become  too  large  for  the  needs  of  your  body.  The 
heart  may  then  wear  itself  out  by  useless  work,  and  may 
finally  become  weaker  than  if  you  had  not  taken  exer- 
cise. Running  long  races  until  you  can  scarcely  stand 
is  an  example  of  the  kind  of  exercise  which  is  harmful. 

Many  famous  athletes  of  schools  and  colleges  have 
injured  their  hearts  by  training  too  hard.  It  is  a  fine 
thing  to  cheer  the  contestants  in  a  sport  or  game,  but 
remember  that  your  cheering  may  lead  the  athletes  to 
overwork  themselves  and  to  injure  themselves  for  life. 

The  Heart  and  Sickness.  —  When  a  person  is  sick, 
the  poisons  of  the  disease  make  his  heart  weak.  The 
heart  then  beats  fast  in  trying  to  supply  the  cells  with 
all  the  blood  that  they  need.  One  of  the  greatest 
dangers  in  a  sickness  is  that  the  heart  may  tire  itself 
out.  The  pulse  is  one  of  the  best  signs  of  the  severity 
of  a  disease.  It  is  a  sign  of  dangerous  sickness  when  the 
heart  beats  hour  after  hour  twice  as  fast  as  during 
health. 


102;  CIRCULATION   OF   BLOOD 

A  person  may  think  that  he  has  heart  disease  when 
he  feels  his  heart  beating  hard,  or  his  pulse  throbbing 
in  his  head.  These  feelings  are  not  always  signs  of 
heart  trouble.  They  are  usually  due  to  overeating,  or 
to  gas  in  the  stomach  pressing  against  the  heart,  and 
they  pass  away  when  the  stomach  does  its  work  prop- 
erly. The  principal  sign  of  real  heart  disease  is  short- 
ness of  breath  caused  by  failure  of  the  blood  to  carry 
oxygen  to  the  cells. 

Blood  Pressure.  -  -  The  heart  forces  blood  through 
the  arteries  with  enough  pressure  to  cause  a  stream  to 
spurt  up  three  or  four  feet  when  a  large  artery  is  cut. 
If  the  blood  pressure  is  increased,  the  heart  must  beat 
hard  in  order  to  force  blood  into  the  tubes.  An  in- 
creased pressure  of  the  blood  also  causes  the  blood  to 
flow  too  fast  for  the  proper  changes  to  take  place  in  the 
capillaries.  Physicians  often  test  the  blood  pressure 
when  they  examine  a  person.  An  increased  pressure 
is  usually  a  sign  of  sickness  and  danger. 

Hardened  Arteries.  —  A  healthy  artery  is  soft  and 
elastic,  like  a  piece  of  new  rubber.  The  walls  of  the 
arteries  of  very  old  persons  usually  become  hardened 
with  lime.  The  arteries  are  then  like  a  piece  of  old 
rubber,  and  are  in  danger  of  bursting,  for  they  cannot 
stretch  when  the  heart  beats  hard.  An  old  person  is 
likely  to  die  of  apoplexy,  caused  by  the  bursting  of  a 
hardened  artery  in  the  brain. 

Many  persons  in  middle  life  suffer  with  hardened 
arteries  and  increased  blood  pressure.  One  of  the 


CIRCULATION   OF  BLOOD 


103 


principal  causes  of  hardened  arteries  and  increased 
blood  pressure  is  continuous  hard  work  and  worry. 
Proper  rest  and  play  are  as  necessary  for  a  busy  grown 
person  as  for  a  schoolboy. 

Alcohol  and  the  Heart.  —  An  alcoholic  drink  seems 
to  increase  the  force  of  the  heart  beats.  Doctors 
formerly  gave  a  great  deal  of  alcohol  to  the  sick.  We 
now  know  that  alcohol  seldom  makes  the  heart  stronger. 
It  seems  to  do  so  because  it  makes  the  arteries  large, 
and  allows  blood  to  flow  through  them  easily.  The 
heart  then  seems  to  have  a  great  deal  of  power,  like 
an  automobile  engine  which  is  running  while  the  car 
stands  still.  But  when  a  strain  is  put  upon  the  heart, 
as  in  climbing  stairs,  the  heart  shows  less  power  than 
when  alcohol  is  not  used.  Doctors  now  give  very  little 
alcohol  to  the  sick. 

Alcohol  and  Arteries.  —  Alcohol  is  a  poison  to  the 
muscles  of  the  arteries,  and  prevents  them  from  con- 
tracting when  they  should.  The  pressure  of  the  blood 
then  stretches  the  arteries  and  makes  them  large. 
Alcohol  makes  a  drinker's  face  red  because  it  increases 
the  size  of  the  arteries  of  the  skin. 

When  the  muscles  of  the  arteries  do  not  act,  the  flow 
of  blood  to  the  various  organs  cannot  be  regulated,  but 
some  organs  will  get  more  blood,  and  others  will  get 
less,  than  they  need.  This  disturbance  of  the  circulation 
is  often  the  cause  of  diseases  of  the  brain,  kidneys,  and 
other  organs. 

Tobacco  and  the  Heart.  —  The  nicotine  of  tobacco 


104  CIRCULATION  OF  BLOOD 

is  a  poison  to  the  muscles  of  the  heart,  just  as  it  is  to 
the  muscles  of  the  arms  and  the  legs.  If  a  great  deal  of 
tobacco  is  used,  the  heart  often  beats  in  an  irregular 
way,  or  skips  a  beat  now  and  then.  Those  persons 
whose  hearts  act  in  this  way  have  great  difficulty  in 
getting  their  lives  insured,  for  they  are  much  more  likely 
to  become  sick  and  to  die  than  those  whose  hearts 
beat  naturally. 


QUESTIONS 

What  is  the  circulation  ? 
Of  what  is  blood  composed  ? 
What  are  red  blood  cells  ?     What  is  their  use  ? 
What  are  white  blood  cells  ?     What  is  their  use  ? 
What  is  plasma  ?     What  is  its  use  ? 
What  effect  does  clotting  have  on  bleeding  ? 
What  are  arteries  ? 

Of  what  use  are  the  muscles  in  the  walls  of  arteries  ? 
What  are  veins  ? 

Of  what  use  are  the  valves  in  veins  ? 

How  does  exercise  help  the  flow  of  blood  through  the  veins  ? 
What  are  capillaries  ? 

What  changes  occur  in  the  blood  while  it  is  passing  through 
the  capillaries  ? 

Describe  the  heart. 

What  is  a  ventricle  ? 

What  is  an  auricle  ? 

Describe  a  heart  beat. 

What  is  the  pulse  ? 

Where  may  the  pulse  be  felt  ? 

What  is  the  difference  between  arterial  and  venous  blood  ? 


CIRCULATION  OF   BLOOD 

Through  what  structures  does  a  drop  of  blood  pass  in  making 
a  complete  round  of  the  circulation  ? 

What  is  lymph  ? 

What  causes  the  lymph  to  flow  in  the  flesh  ? 

Compare  the  circulation  of  blood  in  the  body  with  the  water 
supply  of  a  city. 

What  effect  does  exercise  have  on  the  heart  ? 

What  effect  does  sickness  have  on  the  heart  ? 

What  is  the  cause  of  a  hardening  of  the  arteries  ? 

What  effect  does  alcohol  have  on  the  heart  ?     on  the  arteries  ? 

What  effect  does  tobacco  have  on  the  heart  ? 


CHAPTER  X 

EMERGENCIES 

» 

Panic.  —  Accidents  nearly  always  happen  suddenly, 
and  the  danger  is  usually  over  in  a  very  short  time. 
If  an  accident  happens  in  a  crowd,  one  of  the  greatest 
of  the  dangers  is  that  people  will  hurt  one  another  in 
trying  to  get  away  from  the  place.  Often  those  who  are 
in  an  accident  do  not  take  time  to  think,  but  they  push 
and  throw  each  other  down,  and  in  that  way  they 
often  do  more  harm  than  the  accident  itself.  When 
the  persons  in  a  crowd  become  filled  with  fear  and  act 
without  thinking,  like  a  flock  of  frightened  sheep,  we 
say  that  they  are  in  a  panic.  A  sudden  danger  which 
requires  quick  action  is  called  an  emergency. 

Fire  Drill  at  School.  —  A  cry  of  "  Fire  "  in  a  crowded 
meeting  place  will  often  cause  a  panic.  Lives  have 
sometimes  been  lost  in  panics  when  a  large  number  of 
people  in  a  crowded  hall  have  tried  to  escape  at  once 
from  a  harmless  fire.  Most  panics  are  caused  by  too 
great  a  hurry  to  escape  from  a  supposed  danger.  About 
two  persons  are  all  that  can  go  through  a  doorway  at 
once.  If  half  a  dozen  try  to  crowd  through  at  one 
time,  some  one  is  likely  to  be  hurt. 

Fire  drills  at  school  teach  boys  and  girls  how  to  go 

106 


EMERGENCIES  107 

out  of  a  building  quickly  and  safely.  When  an  alarm 
bell  is  rung,  the  scholars  drop  their  books  and  march  out 
of  the  building  in  good  order.  In  this  way  a  large 
schoolhouse  may  be  emptied  in  less  than  two  minutes. 
This  is  far  less  time  than  it  would  take  a  fire  to  spread 
in  a  dangerous  way. 

The  alarm  bell  for  a  fire  drill  is  rung  at  an  unexpected 
time,  and  the  scholars  do  not  know  whether  there  is  a 
real  fire  or  not.  When  fires  have  occurred  in  school- 
houses  in  which  the  drills  have  been  held  regularly,  the 
scholars  have  always  escaped  in  safety,  because  they 
have  been  trained  to  think  about  what  they  are  to  do. 
The  pupils  have  not  crowded  one  another,  but  each  has 
helped  the  rest  to  act  in  an  orderly  way.  Scholars 
who  have  been  trained  in  this  way  are  likely  to  be  cool 
and  thoughtful  when  an  accident  happens  or  danger 
arises  in  any  place. 

Learning  to  Swim.  —  A  great  many  persons  lose 
their  lives  because  they  do  not  know  how  to  float  in 
the  water.  Many  persons  who  can  swim  lose  their 
lives  in  trying  to  save  those  who  cannot  swim,  but  who 
become  frightened  and  pull  their  rescuers  down  with 
them.  Over  thirty  persons  were  drowned  in  the  New 
England  States  on  a  single  day  of  August,  1910.  Most 
of  them  would  have  been  saved  if  they  had  learned  to  be 
cool  when  in  danger,  and  had  helped  those  who  tried 
to  save  them.  All  of  them  would  have  been  saved  if 
they  had  taken  the  trouble  to  learn  to  swim  while 
they  were  young. 


io8  EMERGENCIES 

You  can  easily  learn  to  float  or  swim  if  you  do  not 
become  frightened  by  a  little  water  in  your  nose  and 
face.  You  cannot  sink  if  you  do  not  breathe  water 
into  your  body  in  the  place  of  air.  The  reason  why 
learning  to  swim  is  hard  is  because  your  head  is 
heavy  and  presses  your  body  deep  into  the  water.  If 
you  had  a  long  nose,  like  a  dog's,  and  could  hold  it 
straight  up,  you  would  learn  to  swim  as  naturally  as 
a  dog  does.  Your  body  sinks  so  low  that  the  water 
comes  nearly  up  to  your  nose  and  frightens  you;  but 
you  are  in  no  danger  so  long  as  your  nose  is  above  the 
water. 

It  is  your  duty  to  learn  to  swim.  Go  to  the  water 
with  a  friend  who  knows  how  to  swim,  and  make  up 
your  mind  that  you  will  not  be  frightened.  Do  as  he 
tells  you,  and  you  will  quickly  learn  to  swim. 

If  a  person  is  nearly  drowned,  you  may  be  able  to 
save  his  life  by  doing  artificial  respiration.  The  way 
to  do  this  is  described  on  page  130. 

Curiosity  of  a  Crowd.  —  When  a  person  is  hurt, 
those  who  are  near  by  often  crowd  around  him  out  of 
curiosity  to  see  what  is  going  on.  This  is  the  wrong 
thing  to  do,  because  it  shuts  off  the  fresh  air  from  the  in- 
jured person,  and  interferes  with  those  who  try  to  help 
him.  When  a  person  is  hurt,  do  not  rush  to  look  at 
him,  but  keep  away  unless  you  are  able  to  help.  If  a 
doctor  or  nurse  is  working  over  the  injured  person, 
you  can  do  no  good  by  looking  on,  but  you  are  likely 
to  do  great  harm. 


EMERGENCIES  109 

How  to  Help  an  Injured  Person.  —  If  you  are  the 

only  person  near  to  some  one  who  is  injured,  you  may  be 
of  great  help  to  him.  There  are  always  three  things 
to  think  about  in  an  accident :  first,  what  is  called  the 
shock  of  the  accident;  second,  bleeding;  and  third, 
broken  bones. 

Shock.  —  A  person  who  falls,  or  is  struck  a  hard  blow, 
or  is  suddenly  hurt  in  any  way,  usually  feels  dizzy, 
short  of  breath,  and  sick,  and  often  does  not  know  any- 
thing at  all  for  a  moment.  This  sickness  is  called 
shock.  If  a  person  is  suffering  from  the  shock  of  an 
accident,  lay  him  down  on  his  back,  so  that  his  heart 
and  breathing  may  go  on  as  undisturbed  as  possible. 
Do  not  rub  him  or  shake  him,  for  that  might  make  the 
shock  worse.  Do  not  force  him  to  swallow  whisky  or 
other  strong  drink.  Alcohol  in  an  accident  seldom  does 
good,  but  it  often  does  great  harm. 

Bleeding.  —  A  great  danger  in  an  accident  is  the 
bleeding  from  a  cut  or  wound.  A  person  may  lose  a 
cupful  of  blood  without  danger,  but  if  he  loses  a  pint, 
he  will  be  weak  and  faint.  Bleeding  from  a  wound 
usually  stops  within  five  minutes,  for  the  blood  clots, 
and  closes  the  open  tubes  (p.  89).  If  a  large  blood  tube 
is  cut,  the  blood  may  flow  so  swiftly  that  the  stream 
washes  away  the  clot  as  fast  as  it  is  formed.  Bleeding 
from  a  cut  artery  is  dangerous,  for  the  blood  spurts  out 
as  if  it  were  forced  from  a  syringe.  Blood  from  a  vein 
does  not  spurt  out,  but  flows  so  slowly  that  it  may 
easily  be  stopped. 


no 


EMERGENCIES 


How  to  Stop  a  Bleeding  Wound.  —  Bleeding  comes 
from  an  open  tube,  and  you  can  always  stop  it  by  press- 
ing or  pinching  the  flesh 
around  the  wound  so  as 
to  close  the  blood  tube. 
Press  a  clean  handkerchief 
against  the  wound,  if  you 
can  get  one.  If  not,  use 
your  bare  hand  or  finger. 
Many  lives  have  been  lost 

S  topping  a  bleeding  by  grasping  the     because  no  One  has  thought 
sides  of  the  cut.  . 

to   do   this  simple   thing. 

Almost  the  only  danger  that  is  likely  to  come  from 
pressing  Upon  a  wound  is  that  dirt  from  your  hands 
might  get  into  the  wound. 
But  you  do  not  need  to 
put  your  fingers  or  hand 
into  a  wound.  You  can 
stop  the  bleeding  by  press- 
ing the  flesh  on  both  sides 
of  the  wound.  Hold  the 
wound  closed  until  you  can 
prepare  a  bandage,  or  until 
help  comes.  In  this  way 
you  can  stop  the  bleeding 
from  the  largest  arteries.  stopping  a  bleeding  by  tying  a 

handkerchief  over  the  wound. 

Bandaging   a  Bleeding 

Wound.  —  After  you  have  held  a  wound  closed  with 
your  fingers  or  hand  for  a  few  minutes,  bind  it  up  with 


EMERGENCIES  in 

a  bandage  which  will  press  upon  the  wound  and  hold 
the  blood  tubes  closed.  You  can  make  the  bandage  by 
crumpling  a  handkerchief  into  a  ball  and  tying  it 
snugly  upon  the  wound  with  another  handkerchief. 

If  several  fingers  or  toes  are  wounded,  or  if  a  whole 
hand  or  a  foot  is  injured  or  cut  off,  you  can  stop  the 
bleeding  by  grasping  the  whole  limb  above  the  bleeding 
part  and  holding  it  tightly  so  as  to  close  the  arteries 
which  carry  blood  to  the  wound.  In  such  a  wound  as 
this  you  may  not  be  able  to  bind  a  bandage  over  the 
wound  itself  tightly  enough  to  keep  the  blood  from 
flowing.  But  you  can  stop  the  bleeding  by  tying  a 
handkerchief  or  cord 
tightly  around  the 
whole  limb  above  the 
wounded  part. 

If  a  bleeding  is  very 
bad  you  can  tie  a  cord 
or  handkerchief  loosely 
around  the  limb  and 
make  it  as  tight  as  you 
choose  by  thrusting  a 

Stick      Under      it      and     Stopping    a    bleeding   by    tying  a  cord 

tightly  around  the  limb. 

twisting    it.      If    you 

have  to  do  this,  watch  it  carefully,  and  do  not  make  it 
any  tighter,  or  keep  it  on  any  longer,  than  is  necessary, 
for  the  pressure  of  the  cord  is  both  painful  and  dan- 
gerous. Send  for  a  doctor  as  soon  as  possible. 

Cleanliness  of  Wounds.  —  Some  persons  try  to  stop 


112 


EMERGENCIES 


a  bleeding  place  by  placing  spider  webs  or  other  un- 
clean substances  over  the  wound.  This  is  extremely 
dangerous,  for  the  dust  and  dirt  in  them  are  often  full 
of  disease  germs.  Dirty  bandages  also  contain  disease 
germs.  If  you  have  to  use  a  soiled  bandage  to  stop  a 
dangerous  bleeding,  change  it  for  a  clean  one  as  soon 
as  possible.  Boiling  a  bandage  will  kill  the  disease 
germs  even  if  it  does  not  make  the  bandage  look  clean. 
Sometimes  the  skin  around  a  wound  is  dirty,  or 
there  is  dirt  in  the  wound.  Do  not  try  to  cleanse  the 
wound,  unless  you  use  water  which  has  been  boiled. 
Dress  the  wound  without  trying  to  wash  away  the 
blood.  The  blood  itself  will  be  a  good  dressing,  and  will 
help  to  kill  the  disease  germs  which  may  be  in  the  dirt. 
Send  for  a  doctor  as  soon  as  possible,  and  let  him 
cleanse  the  wound. 

Nose   Bleed.  —  Blood   in    a   bleeding   nose   nearly 
always  comes  from  an  open  vein.     If  you  have  a  nose 

bleed,  you  can  stop  it  by  holding 

your  nostrils  closed  with  your 
thumb  and  finger  for  about  five 
minutes  while  you  breathe  through 
your  mouth.  This  will  close  the 
vein  and  allow  the  blood  to  clot 
in  it. 

Do  not  sit  bent  over  while  your 
nose  is  bleeding,  for  that  will  al- 
low a  great  deal  of  blood  to  flow 
stopping  a  nose  bleed.      to  your  head  and  nose ;    but  sit 


EMERGENCIES  113 

up  straight  to  keep  the  blood  away  from  your  head. 
Do  not  blow  your  nose  hard  for  some  time  after  the 
bleeding  has  stopped,  for  that  would  blow  the  clot 
away  from  the  vein  and  start  the  bleeding  again. 

Broken  Bones.  —  When  a  person  has  been  hurt,  try 
to  find  out  whether  or  not  his  bones  are  injured.  A 
broken  bone  is  not  dangerous  to  life  unless  it  sticks 
through  the  flesh,  but  it  is  always  painful.  Sprains, 
and  bones  out  of  joint,  are  also  painful,  but  not  dan- 
gerous to  life. 

You  may  lessen  the  pain  of  a  sprain,  or  of  a  bone  out 
of  joint,  by  bandaging  a  stick  or  thin  board  to  the  limb 
in  such  a  way  that  it  keeps  the  injured  part  at  rest 
(p.  74).  Then  the  person  may  be  moved  with  comfort 
and  safety. 

Fainting.  —  A  person  who  is  weak,  or  sick,  or  hurt, 
or  frightened,  sometimes  looks  pale,  feels  dizzy,  and 
falls  down  and  knows  nothing  for  a  few  seconds.  We 
then  say  that  he  has  fainted.  What  has  happened  is 
that  the  heart  has  suddenly  become  weak  and  has 
failed  to  send  blood  to  the  head,  and  the  mind  has 
stopped  acting  for  a  moment. 

When  a  person  faints,  lay  him  down  and  keep  his 
head  low,  so  that  blood  will  flow  to  it.  Rub  his  body, 
or  throw  cold  water  into  his  face,  so  as  to  rouse  him. 
In  a  moment  his  heart  will  begin  to  beat  strongly, "and 
he  will  soon  feel  well  again. 

Fits  and  Convulsions.  —  Sometimes  a  person  sud- 
denly falls  down,  his  arms  and  legs  stiffen  and  shake, 

GEN.   HYG. — 8 


EMERGENCIES 

and  his  face  twitches  as  if  he  were  in  pain.  We  then 
say  that  he  has  a  fit,  or  convulsion.  The  stiffness  and 
twitching  are  caused  by  contractions  of  the  muscles 
of  the  whole  body.  While  a  person  is  in  a  fit,  he  knows 
nothing  and  does  not  suffer. 

A  fit  in  a  grown  person  is  usually  caused  by  a  brain 
trouble  called  epilepsy.  While  a  person  is  in  a  fit  of 
epilepsy,  almost  the  only  danger  is  that  he  may  bite 
his  tongue  or  cheeks.  You  may  prevent  this  by  press- 
ing a  handkerchief  into  his  mouth,  so  as  to  keep  the 
tongue  away  from  the  teeth.  You  can  do  nothing 
to  bring  a  person  out  of  a  fit,  but  in  a  minute  or  two 
the  fit  usually  passes  off,  and  the  person  feels  well 
again. 

A  fit  in  a  baby  is  usually  caused  by  spoiled  food  in 
its  digestive  organs,  and  usually  stops  when  the  cause 
is  removed. 

Hysterics.  —  There  is  a  kind  of  fit,  called  hysterics, 
in  which  a  person  laughs  and  cries,  and  also  moves  the 
body  as  in  a  real  fit.  But  the  person  who  has  it  knows 
what  is  going  on,  while  in  real  fits  he  knows  nothing  at 
all.  Hysterics  are  usually  caused  by  fear,  or  worry. 
The  person  who  has  them  acts  like  a  spoiled  child  that 
throws  itself  on  the  floor,  and  kicks  and  cries. 

There  is  no  danger  from  hysterics.  Keep  yourself 
calm  and  cool  headed,  and  act  toward  the  sick  person 
just  as  you  would  toward  a  spoiled  child. 


EMERGENCIES  115 

QUESTIONS 

What  is  a  panic? 

Of  what  use  are  fire  drills  at  school  ? 

Give  some  reasons  why  every  boy  and  girl  should  learn  to 
swim. 

Why  is  it  harmful  to  an  injured  person  for  a  crowd  to  gather 
around  him  ? 

What  is  meant  by  shock  when  a  person  meets  with  an  ac- 
cident ? 

What  should  you  do  for  shock  ? 

How  can  you  stop  a  bleeding  wound  with  your  bare  hands  ? 

How  should  you  apply  a  dressing  to  a  wound  in  order  to 
stop  its  bleeding  ? 

If  an  arm  or  leg  is  badly  wounded,  how  can  you  stop  the 
bleeding  ? 

How  should  you  stop  a  nose  bleed  ? 

What  harm  may  dirty  dressings  do  to  a  wound  ? 

How  should  you  help  a  person  who  has  a  broken  bone  ? 

What  is  the  trouble  with  the  circulation  of  the  blood  in  a 
person  who  is  in  a  faint  ? 

How  should  you  help  a  person  who  is  faint  ? 

What  is  a  fit  ? 

What  should  you  do  to  help  a  person  who  is  in  a  fit  ? 

What  is  a  fit  of  hysterics  ? 

How  can  you  tell  hysterics  from  a  real  fit  ? 

What  should  you  do  for  a  person  who  has  hysterics  ? 


CHAPTER  XI 


RESPIRATION 

The  Lungs.  —  Every  cell  in  the  body  must  have 
oxygen  in  order  to  live.  The  oxygen  is  taken  from  the 
air  by  means  of  the  organs  called  the  lungs,  and  is 

carried    through    the 
body  by  the  blood. 

The  lungs  are  two 
organs  into  which  air 
is  drawn  by  the  act  of 
breathing.  They  are 
composed  of  millions 
of  microscopic  air  sacs 
whose  walls  are  thin, 
and  are  covered  with 
capillaries.  The  red 
blood  cells,  passing 
through  the  capilla- 
ries, take  oxygen  from 

the  air  in  the  sacs  (p.  89).  If  the  air  sacs  of  the 
lungs  were  all  opened  and  spread  out,  they  would 
cover  a  surface  sixty  times  as  large  as  the  skin  on  the 
outside  of  the  body. 

116 


Capillaries  and  air  sacs.     Magnified. 


RESPIRATION 


117 


Air  Tubes.  —  Air  reaches  the  lungs  by  passing  from 
the  nose  and  throat  through  a  tube  called  the  wind- 
pipe or  trachea.  The 
windpipe  begins  in  a 
box,  called  the  larynx, 
in  which  the  sound  of 
the  voice  is  made.  A 
lid,  called  the  epiglottis, 
closes  over  the  larynx 
during  swallowing,  and 
helps  to  keep  food  from 
dropping  into  the  wind- 


pipe. 


Capillaries  on  air  sacs.    Magnified. 


The  lower  end  of  the  windpipe  is  divided  into  two 

tubes,  called  bronchi,  one  for 
each  lung.  The  bronchi 
divide  again  and  again,  and 
their  smallest  branches  end 
in  the  air  sacs. 

The  windpipe  and  bronchi 
are  lined  with  mucous  mem- 
brane, whose  glands  produce 
an  abundance  of  thin  mucus 
(p.  25).  One  of  the  princi- 
pal uses  of  the  mucus  is  to 
catch  dust  which  may  enter 
the  tubes  with  the  air.  The 
substance  which  is  coughed  up  during  a  cold  is  com- 
posed mostly  of  mucus. 


Lung  of  a  frog. 


n8 


RESPIRATION 


The  structure  of  a  human  lung  may  be  illustrated  by 
the  lungs  of  a  frog  and  of  a  turtle. 

A  frog's  lung  is  a 
thin-walled  sac,  about 
the  size  of  the  last  joint 
of  a  person's  finger. 
Its  inner  surface  is 
marked  off  into  shallow 
spaces  with  low  parti- 
tions over  which  arter- 
ies and  capillaries  run. 
The  whole  lung  is  like  a 
single  air  sac  in  a  human 
Lung  of  a  turtle.  lung  greatly  magnified. 

A  turtle's  lung  is  divided  into  a  great  number  of 
large  air  spaces  by  thin  walls  which  extend  in  every 
direction  through  the  lung.  Each  air  space  is  like  an 
enlarged  air  sac  in  a  human 
lung. 

Cilia. --The  mucous 
membrane  of  the  bronchi 
is  lined  with  short  threads 
•of  flesh  which  stand  up 
from  the  epithelial  cells, 
like  the  threads  upon  vel- 
vet cloth  (p.  25).  These 
threads  are  called  cilia. 
They  wave  swiftly  back  and  forth,  and  help  to  force 
the  mucus  from  the  tubes.  In  this  way  they  keep 


Cilia. 


RESPIRATION  119 

the  bronchi  clean,  and  prevent  dust  from  entering  the 
air  sacs. 

The  Chest  or  Thorax. --The  hollow  space  in  the 
upper  part  of  the  trunk  of  the  body  is  called  the  chest, 
or  thorax.  Its  back  wall  is  formed  by  the  backbone, 
its  sides  by  the  ribs,  and  its  front  side  by  the  breast- 
bone, or  sternum.  Its  bottom  is  formed  by  a  sheet  of 
muscle,  called  the  diaphragm,  which  extends  across  the 
body  in  the  form  of  a  dome  at  about  the  level  of  the 
waist.  The  chest  contains  the  lungs  and  the  heart. 

Breathing. -- The  ribs  are  joined  together  by  flat 
muscles,  called  the  intercostal,  or  rib,  muscles.  When 
the  muscles  contract,  they  raise  the  outer  ends  of  the 
ribs,  and  increase  the  size  of  the  chest.  When  the  dia- 
phragm contracts,  it  flattens  its  arch,  and  also  increases 
the  size  of  the  chest. 

The  air  sacs  of  the  lungs  are  always  filled  so  full  of 
air  that  the  sides  of  the  lungs  are  kept  pressed  against 
the  ribs  and  diaphragm.  When  the  chest  increases 
in  size,  air  rushes  into  the  lungs,  and  when  the  chest 
muscles  relax,  the  chest  becomes  smaller,  and  forces 
some  of  the  air  out  of  the  lungs.  The  passage  of  air 
into  and  out  of  the  lungs  is  called  breathing.  Taking 
air  into  the  lungs  is  called  inspiration,  and  forcing  air 
out  of  the  lungs  is  called  expiration.  A  person  usually 
breathes  from  fifteen  to  twenty  times  each  minute. 

How  Cells  Breathe.  —  While  blood  is  passing  through 
the  lungs,  its  red  blood  cells  take  up  oxygen  from  the 
air  sacs.  The  blood  then  goes  back  to  the  heart,  and 


120  RESPIRATION 

then  through  the  arteries  to  all  parts  of  the  body. 
When  it  reaches  the  capillaries,  it  gives  up  the  oxygen 
to  the  cells. 

The  cells  in  all  parts  of  the  body  use  oxygen  to 
oxidize  both  their  own  substance,  and  also  the  food 
which  they  receive  from  the  blood.  One  of  the  princi- 
pal substances  which  the  oxidation  produces  is  carbon 
dioxide  (p.  32).  The  blood  takes  up  the  carbon  di- 
oxide and  carries  it  through  the  veins,  back  to  the  heart, 
and  to  the  lungs,  and  gives  it  off  to  the  air  sacs.  It 
then  passes  out  from  the  body  with  the  breath  of  the 
next  expiration. 

Summary  of  the  Changes  produced  by  Breathing.  — 
During  inspiration,  the  lungs  receive  oxygen.  During 
expiration,  the  lungs  give  off  carbon  dioxide. 

The  air  sacs  of  the  lungs  give  oxygen  to  the  blood, 
and  receive  carbon  dioxide  from  it. 

In  the  lungs  the  blood  takes  oxygen,  and  gives  off 
carbon  dioxide. 

In  the  capillaries  of  the  body  blood  gives  off  oxygen 
and  takes  up  carbon  dioxide  and  other  waste  substances. 

The  cells  of  the  body  take  oxygen  from  the  blood,  and 
give  carbon  dioxide  and  other  oxidized  substances  to  it. 

Breathing  and  Health.  -  -  The  strength  of  the  body 
comes  from  the  oxidation  in  it  (p.  32).  When  you  sit 
still  and  do  not  breathe  much  oxygen  into  your  body, 
or  when  you  eat  more  food  than  you  can  oxidize,  the 
oxidation  in  your  body  takes  place  in  an  imperfect 
manner,  and  the  waste  substances  produced  by  the 


RESPIRATION  121 

oxidation  are  more  poisonous  than  they  should  be 
(p-  33)-  You  then  feel  dull,  stupid,  and  weak.  You 
can  neither  think  clearly,  nor  do  good  work  with  your 
muscles.  Your  blood  cells  will  not  easily  destroy  dis- 
ease germs  which  may  enter  your  body,  and  you  will 
take  diseases  readily. 

When  oxidation  takes  place  in  a  perfect  manner,  you 
feel  bright  and  active,  you  enjoy  your  work  and  play, 
and  your  body,  easily  protects  itself  against  diseases. 
Breathing  properly  is  one  of  the  best  means  of  keeping 
yourself  in  good  health. 

Shortness  of  Breath.  —  When  you  take  exercise, 
you  use  up  a  great  deal  of  oxygen  in  supplying  your 
muscles  with  power  and  warmth  (p.  81).  When  you 
exercise  hard,  your  blood  may  not  be  able  to  carry  oxy- 
gen so  fast  as  your  muscles  use  it.  You  then  feel 
short  of  breath  and  cannot  breathe  deeply  enough,  or 
often  enough,  to  supply  your  muscles  with  all  the  oxy- 
gen that  they  need.  The  first  sign  that  your  strength 
is  failing  is  nearly  always  a  shortness  of  breath. 

You  can  increase  your  strength  and  endurance,  as 
well  as  your  health,  by  doing  those  things  which  will 
help  your  blood  to  take  up  a  great  deal  of  oxygen. 
The  principal  ways  of  doing  this  are  by  practicing  deep 
breathing  and  by  taking  exercise.  In  these  two  ways 
you  can  take  a  large  amount  of  oxygen  into  your  body, 
and  you  can  also  cause  oxidation  to  take  place  in  a 
perfect  way  (p.  83). 

Deep  Breathing.  —  When  you  take  brisk  exercise, 


122  RESPIRATION 

you  soon  feel  short  of  breath,  and  cannot  help  breath- 
ing deeply  and  taking  a  large  amount  of  air  into  your 
lungs.  One  of  the  greatest  benefits  from  exercise  is 
that  it  compels  you  to  breathe  deeply. 

If  you  have  to  sit  at  a  desk  all  day,  and  have  but  little 
time  for  exercise,  you  can  increase  the  oxidation  in  your 
body  by  taking  deep  breaths  often.  When  you  begin 
to  feel  dull,  sit  up  straight,  take  a  deep  breath,  and  hold 
it  as  long  as  possible.  This  will  stretch  the  air  sacs 
of  your  lungs  wide  open,  and  will  fill  them  with  a  large 
amount  of  oxygen  which  the  blood  will  carry  through 
every  part  of  your  body. 

Most  lung  diseases  are  caused  by  disease  germs  which 
enter  the  lungs  with  impure  air.  If  the  lungs  do  not 
receive  a  large  quantity  of  air,  the  disease  germs  will 
lie  quietly  in  the  air  sacs  and  the  smaller  air  tubes,  and 
will  grow  there  undisturbed.  But  deep  breathing  will 
stir  up  the  germs,  and  drive  them  out  of  the  lungs. 
The  movements  of  breathing  will  cause  the  blood  to 
flow  freely  among  all  the  air  sacs  where  its  white  blood 
cells  will  destroy  the  disease  germs  which  may  enter 
the  sacs.  Deep  breathing  is  one  of  the  best  of  all 
means  for  preventing  lung  diseases. 

Alcohol  and  the  Lungs.  — The  air  tubes  and  lungs 
receive  more  disease  germs  than  most  other  parts  of 
the  body.  The  stomach  can  protect  itself  against 
disease  germs  which  are  swallowed,  for  its  digestive 
juices  destroy  the  germs.  But  the  lungs  have  only 
the  white  blood  cells  for  protection  against  the  germs. 


RESPIRATION  123 

Alcohol  in  the  blood  weakens  the  white  blood  cells  and 
prevents  them  from  destroying  disease  germs.  The 
use  of  alcohol  is  therefore  harmful  to  the  lungs. 
Drinkers  are  more  likely  to  have  diseases  of  the  lungs 
than  those  who  do  not  take  strong  drink.  Whisky, 
wine,  and  beer  do  not  help  a  person  who  has  a  cold, 
but  they  make  the  cold  worse. 

Tobacco  Smoking.  —  When  tobacco  is  burned,  some 
of  its  nicotine  is  turned  to  vapor  and  is  drawn  into  the 
mouth.  When  the  smoke  is  blown  from  the  mouth, 
some  of  the  nicotine  remains  behind,  and  is  swallowed. 
It  then  enters  the  blood,  like  food  that  is  swallowed. 
Tobacco  smoke  also  contains  other  harmful  substances 
besides  nicotine. 

The  smoke  from  a  cigar  usually  contains  less  nicotine 
than  that  from  a  pipe,  and  smoke  from  a  cigarette  con- 
tains still  less,  for  the  fire  on  the  cigarette  is  hotter  and 
burns  up  more  of  the  nicotine  than  the  fire  on  a  cigar 
or  pipe.  But  those  who  smoke  cigarettes  often  draw 
the  smoke  into  their  lungs  and  blow  it  from  their  noses. 
When  a  person  smokes  a  cigarette  in  this  way,  he  usually 
takes  more  nicotine  into  his  blood  than  he  does  when 
he  smokes  a  cigar  or  a  pipeful  of  tobacco.  The  smoke 
from  a  cigar  or  pipe  has  a  stinging  taste  and  smell,  and 
few  persons  care  to  draw  it  into  their  lungs  to  blow  it 
through  their  noses.  Cigarette  smoke  is  more  harmful 
than  smoke  from  a  cigar  or  pipe,  because  it  has  less 
of  a  stinging  taste  or  smell,  and  the  smoke  seems  the 
more  pleasant,  when  really  it  is  the  more  dangerous. 


124  RESPIRATION 

QUESTIONS 

What  are  the  lungs? 

What  is  the  larynx?  the  trachea? 

What  are  the  bronchi? 

What  are  cilia? 

What  is  the  diaphragm? 

How  does  a  person  make  air  pass  into  and  out  of  the  lungs  ? 

How  does  oxygen  pass  from  the  lungs  to  the  cells  of  the  body  ? 

What  do  the  cells  of  the  body  do  with  the  oxygen  which  they 
receive  ? 

Of  what  use  is  oxidation? 

How  can  you  increase  the  oxidation  in  your  body  ? 

How  does  exercise  of  the  muscles  help  the  oxidation  in  the 
body? 

What  is  the  cause  of  shortness  of  breath  ? 

What  good  effects  are  produced  by  practicing  deep  breath- 
ing? 

How  does  deep  breathing  help  the  lungs  to  destroy  disease 
germs  ? 

What  effect  does  alcohol  have  upon  the  lungs  ? 

What  becomes  of  the  nicotine  of  tobacco  when  a  pipe,  cigar, 
or  cigarette  is  smoked  ? 

Why  is  cigarette  smoke  usually  more  harmful  than  smoke 
from  a  cigar  or  pipe  ? 


CHAPTER  XII 
HINDRANCES  TO  BREATHING 

Stooped  Shoulders.  —  If  you  allow  your  shoulders  to 
fall  forward,  their  weight  and  the  weight  of  your  arms 
will  press  upon  your  chest,  and  you  will  be  unable  to 
breathe  freely.  Take  as  deep  a  breath  as  you  can  while 
you  sit  with  your  shoulders  bent  forward  and  resting 
on  your  chest.  Then  throw  your  shoulders  back  and 
see  how  much  more  air  you  can  take  into  your  lungs. 

When  you  sit  up  straight,  the  muscles  of  your  back 
will  hold  your  shoulders  up,  and  will  also  help  to  raise 
the  ribs  when  you  take  a  deep  breath.  When  you  bend 
over  your  work,  do  not  let  your  shoulders  fall  forward 
on  your  chest.  Keep  them  thrown  back  and  your 
elbows  at  your  side.  You  will  then  be  able  to  breathe 
freely,  even  though  you  have  to  bend  forward  while 
you  work. 

Tight  Clothing.  —  If  your  clothing  is  tight,  you  can- 
not move  your  chest  freely,  and  cannot  breathe  deeply. 
Half  of  the  movements  of  breathing  are  done  by  flatten- 
ing the  diaphragm  and  moving  the  parts  of  the  body 
below  the  waist  line.  Girls  who  lace  their  waists 
tightly  interfere  with  their  breathing  almost  as  much  as 
they  would  if  they  should  lace  their  chests. 

125 


126  HINDRANCES   TO   BREATHING 

Measurement  of  Breathing.  -  -  There  are  two  easy 
ways  of  measuring  the  quantity  of  air  which  you  take 
into  your  lungs.  One  way  is  by  passing  a  tape  measure 
around  your  chest  under  your  arms  and  noting  the 
size  of  your  chest  before  taking  a  breath,  and  again 
after  taking  it.  An  expansion  of  three  inches  is  large 
for  a  twelve-year-old  boy.  An  expansion  of  less  than 
two  inches  is  too  little  for  him. 

Another  way  of  measuring  the  air  which  you  breathe 
is  to  fill  a  large  glass  jar  with  water  and  turn  it  upside 
down  in  a  shallow  pan  of  water  in  such  a  way  that  the 
water  remains  in  the  jar.  Then  pass  a  rubber  tube 
under  the  water,  into  the  jar,  and  blow  through  it.  As 
air  enters  the  jar,  the  water  passes  out.  By  measuring 
the  distance  the  water  sinks  in  the  jar  you  can  tell  how 
much  air  you  breathe  out  from  your  lungs. 

When  a  man  sits  still  at  a  desk  and  breathes  quietly,  he 
expands  his  chest  about  half  an  inch,  and  inhales  about 
thirty  cubic  inches,  or  a  pint  of  air  with  each  breath. 
When  a  strong  man  takes  a  very  deep  breath,  he  ex- 
pands his  chest  four  or  five  inches,  and  inhales  from  two 
to  four  quarts  of  air. 

A  single  deep  breath  of  air  will  last  your  body  less 
than  a  minute.  You  cannot  store  oxygen  in  your  body, 
for  you  use  it  up  as  fast  as  you  breathe  it,  and  must 
take  it  into  your  body  at  the  moment  when  you  make 
use  of  it.  Your  strength  and  endurance  will  depend  on 
how  much  oxygen  you  can  take  into  your  body.  If 
you  can  expand  your  chest  only  an  inch,  and  can  take 


HINDRANCES   TO   BREATHING 


127 


only  a  quart  of  air  at  a  full  breath,  you  will  not  be 
strong  and  healthy.  If  you  take  exercise,  and  practice 
deep  breathing,  you  will  soon  be  able  to  expand  your 
lungs  three  or  four  inches.  Your  body  will  then  re- 
ceive an  abundance  of  oxygen,  and  you  will  be  strong 
and  long  winded. 

Mouth  Breathing. — The  lining  of  the  nose  is  crum- 
pled into  folds,  and  is  moistened  with  mucus.  As  air 
passes  over  the  folds,  it 
is  warmed  and  mois- 
tened, and  most  of  the 
dust  and  disease  germs 
which  may  be  in  it  are 
caught  in  the  mucus. 
When  the  breath  passes 
through  the  mouth,  the 
air  enters  the  lungs  cold 
and  dusty.  Mouth 
breathing  is  harmful  to 
the  lungs,  and  is  the 
cause  of  a  great  deal  of 
ill  health. 

Every     person     will 

, ,  ,  ,  Folds  of  bone  in  the  nose  of  a  calf. 

naturally      breathe 

through  his  nose  if  it  is  clear  and  open.  If  he  breathes 
through  his  mouth,  it  is  because  his  nose  is  partly 
stopped  up.  A  stopped-up  nose  always  feels  uncom- 
fortable, and  breathing  through  the  mouth  requires  an 
effort.  A  child  at  school  cannot  put  his  mind  upon 


128 


HINDRANCES   TO   BREATHING 


his  lessons  if  he  has  to  think  about  his  breathing  every 
moment. 

Your  nose  may  be  stopped  up  with  mucus.  If  this 
is  so,  remove  the  mucus  by  blowing  it  out. 

If  your  nose  remains  stopped  up  after  blowing  it 
lightly  two  or  three  times,  the  stoppage  is  probably 
caused  by  a  swelling  of  its  lining.  This  swelling  is 
usually  due  to  an  extra  amount  of  blood  in  the  nose. 
Blowing  the  nose  hard  will  send  more  blood  to  it,  and 
will  make  its  swelling  worse.  You  can  make  the  swell- 
ing go  down  by  blowing  out  all  the  breath  that  you  can, 
and  then  waiting  as  long  as  you  can  before  you  take 

another  breath. 
The  chest,  in  try- 
ing to  expand,  will 
draw  blood  away 
from  the  head. 
The  blood  tubes 
of  the  nose  will 
then  be  emptied, 
and  the  swelling  of 
the  lining  will  go 
down. 

Adenoids.  — 
Mouth  breathing 
is  often  caused  by 
masses  of  soft  flesh, 

called  adenoids,  growing  in  the  back  part  of  the  throat 
behind  the  nose.     Children  who   hold  their  mouths 


Model  of  the  nose  and  throat. 


HINDRANCES    TO   BREATHING 


129 


Adenoids  and  enlarged  tonsils  removed   from 
a  three-year-old  boy. 


open  while  they  breathe,  and  who  snore  in  their  sleep, 
nearly  always  have  adenoids.  What  is  called  catarrh 
is  usually  due  to  adenoids.  They  are  often  the 
cause  of  colds,  sore 
throats,  and  deaf- 
ness. They  may  be 
removed  as  quickly, 
safely,  and  pain- 
lessly as  a  tooth 
may  be  pulled. 
Their  loss  does  not 
produce  any  bad 
effects,  for  they  are 
of  no  use  to  the 
body.  A  person 
from  whom  they  are  taken  out  is  left  in  the  same  state 
as  one  who  has  not  had  adenoids  at  all.  After  a  child 
has  had  his  adenoids  removed,  there  is  nearly  always  a 
remarkable  improvement  in  his  health,  strength,  and 
appearance. 

Enlarged  Tonsils. — Two  round  masses  of  flesh, 
about  the  size  of  black  walnuts,  may  extend  from  the 
sides  of  the  throat  and  almost  meet  over  the  back  of 
the  tongue.  These  masses  are  called  enlarged  tonsils. 
They  interfere  with  breathing  and  speaking,  just  as  if 
marbles  were  held  in  the  throat.  They  are  nearly 
always  full  of  holes  in  which  disease  germs  often  lodge 
and  grow,  producing  the  bad  form  of  sore  throat  called 
tonsillitis.  Those  who  have  enlarged  tonsils  nearly 

GEN.   HYG. Q 


130  HINDRANCES   TO   BREATHING 

always  have  adenoids.     The  tonsils  may  be  removed  as 
easily  and  with  as  much  benefit  as  adenoids. 

Artificial  Respiration.  —  A  person  who  has  been 
nearly  drowned  may  be  brought  back  to  life  by  causing 
air  to  pass  into  and  out  of  his  lungs,  as  in  natural 
breathing.  Causing  a  person's  chest,  to  move  in  imita- 
tion of  natural  breathing  is  called  artificial  respiration. 


'"       • : : : J 

Artificial  respiration.     Inspiration.     Drill  by  the  crew  of  a  U.  S.  Life  Sav- 
ins' Station. 


ing  Station 

If  you  know  how  to  do  artificial  respiration,  you  may 
be  able  to  save  the  life  of  a  drowning  person  when  no 
one  else  is  near  (p.  108). 

One  of  the  best  ways  of  doing  artificial  respiration 
is  to  lay  the  drowned  person  on  his  back,  grasp  his  arms 
near  his  elbows,  and  press  them  hard  against  his  chest. 
This  produces  expiration.  Then  carry  the  arms 
straight  out  above  his  head.  This  raises  his  chest 
-and  draws  air  into  his  lungs.  Make  these  movements 
about  as  often  as  you  naturally  breathe.  Do  not  stop 


HINDRANCES    TO   BREATHING  131 

if  life  does  not  return  within  a  few  moments.  Drowned 
persons  have  been  saved  after  artificial  respiration  has 
been  done  on  them  for  over  an  hour. 


Artificial  respiration.     Carrying  the  arms  forward  in  expiration. 

While  you  are  doing  artificial  respiration,  it  will  be 
a  good  plan  to  have  some  one  assist  you  by  pulling  the 


Artificial  respiration.     Lifting  the  body  to  let  the  water  run  from  the  lungs. 


132  HINDRANCES   TO   BREATHING 

drowned  person's  tongue  forward  every  time  you  carry 
the  arms  above  his  head.  This  will  help  to  open  the 
windpipe. 

There  will  be  some  water  in  the  lungs  of  a  drowning 
person.  Every  few  moments  turn  him  on  his  face  and 
lift  his  body  by  grasping  the  chest  just  back  of  his 
shoulders,  so  as  to  let  the  water  run  from  his  mouth. 
But  do  not  stop  doing  the  artificial  respiration  for  more 
than  a  few  seconds  at  a  time. 

Practice  doing  artificial  respiration  on  each  other, 
so  that  you  will  know  how  to  do  it  if  you  are  ever  called 
to  help  save  a  drowning  person. 

Electric  Shock.  —  If  a  person  has  received  a  strong 
shock  of  electricity,  his  life  is  in  danger  because  he  can- 
not breathe.  You  may  be  able  to  save  his  life  by  doing 
artificial  respiration. 

Alcohol  and  Oxidation.  —  Alcohol  will  readily  unite 
with  oxygen  and  will  burn  with  a  hot  flame.  An 
alcohol  lamp  burns  alcohol  which  is  drawn  up  a  cotton 
wick.  The  wick  hardly  burns  at  all,  for  oxygen  unites 
with  the  alcohol  instead  of  the  cotton  of  the  wick. 

When  alcohol  enters  the  body,  it  becomes  oxidized 
quickly,  and  uses  up  the  oxygen  which  would  otherwise 
oxidize  food  and  flesh.  If  the  proper  food  is  not  oxi- 
dized, the  body  will  suffer.  The  use  of  alcohol  deprives 
the  body  and  its  food  of  oxygen  and  produces  the  same 
harjnful  effects  that  breathing  too  little  oxygen  will 
produce. 


HINDRANCES   TO   BREATHING 


QUESTIONS 

How  do  stooped  shoulders  interfere  with  breathing  ? 

How  does  tight  clothing  interfere  with  breathing  ? 

How  many  inches  should  a  twelve-year-old  boy  be  able  to 
expand  his  lungs  ? 

About  how  many  pints  of  air  can  a  strong  man  take  into  his 
lungs  with  each  breath  ? 

How  long  will  a  deep  breath  of  air  last  the  body  ? 

What  harm  comes  from  breathing  through  the  mouth  ? 

What  are  three  common  causes  which  prevent  a  person  from 
breathing  through  the  nose  ? 

How  can  you  cause  your  nose  to  become  open  when  it  is 
stopped  up  ? 

What  are  adenoids? 

What  harm  do  adenoids  do  ? 

How  can  you  get  rid  of  adenoids  ? 

What  are  enlarged  tonsils? 

What  harm  do  enlarged  tonsils  do  ? 

How  can  you  save  the  life  of  a  drowning  person  ? 

Describe  how  to  do  artificial  respiration. 

What  would  you  do  for  a  person  who  has  received  a  bad 
shock  of  electricity  ? 

What  effect  does  alcohol  have  on  the  oxidation  in  the  body  ? 


CHAPTER  XIII 

FOUL  AIR 

Composition  of  Fresh  Air.  —  Outdoor  air  is  made 
up  of  about  one  fifth  oxygen  and  four  fifths  nitrogen. 
About  one  hundredth  of  it  is  vapor  of  water,  and  one 
twenty-five  hundredth  is  carbon  dioxide.  A  few  bac- 
teria, and  some  particles  of  dust  are  nearly  always 
floating  in  it.  All  these  substances  enter  the  nose  and 
air  tubes  during  breathing. 

Oxygen  is  the  part  of  the  air  which  supports  life 
and  oxidation.  When  the  end  of  a  red-hot  iron  wire 
is  thrust  into  a  jar  of  oxygen,  the  wire  burns  like  a 
match,  and  throws  off  a  shower  of  sparks.  If  a  stove 
were  set  up  in  a  room  full  of  oxygen,  its  iron  would 
burn  up  if  a  fire  were  started  in  it.  If  we  should 
breathe  pure  oxygen,  the  oxidation  in  our  bodies  would 
take  place  too  rapidly  for  health.  The  effect  of  the 
nitrogen  of  the  air  is  to  dilute  the  oxygen,  and  make  it 
act  in  a  mild  way. 

Composition  of  Expired  Air.  —  Oxygen  forms  about 
one  fifth  of  the  air  which  is  taken  into  the  lungs  during 
breathing,  but  it  forms  only  about  one  sixth  of  the  air 
which  is  breathed  out  from  the  lungs.  The  difference 
between  one  fifth  and  one  sixth,  or  one  thirtieth,  stands 

134 


FOUL  AIR 


135 


for  that  part  of  the  air  which  enters. the  blood  while 
a  breath  remains  in  the  lungs. 

Since  the  amount  of  air  in  a  quiet  breath  measures 
about  thirty  cubic  inches,  and  one  thirtieth  of  it  goes 
into  the  blood,  the  amount  of  oxygen  which  enters 
the  blood  with  each  breath  measures  about  one  cubic 
inch. 

Carbon  dioxide  forms  a  very  small  part  of  outdoor 
air,  but  it  forms  about  one  thirtieth  of  the  air  which  is 
breathed  from  the  lungs.  Thus  the  amount  of  carbon 
dioxide  which  leaves  the  lungs  with  each  breath  is  about 
one  cubic  inch. 

Expired  air  is  loaded  with  vapor  of  water,  and  con- 
tains a  small  quantity  of  poisonous  substances  which 
give  it  a  bad  odor.  It  is  usually  warmer  than  in- 
spired air. 


SUBSTANCES  AND  QUALITIES  OF  THE  AIR 

INSPIRED  AIR 

EXPIRED  AIR 

Nitrogen     i,     . 

1 

± 

Oxygen  .                               ...     » 

i 

i 

Carbon  dioxide                             .     < 

'Z'STFO 

& 

Moisture     .    ^     ,                        .    •* 

Usually  dry 

Very  moist 

Odor  .     .     ,    .          ....*. 

None          -  -j  -  • 

Considerable 

Warmth      .""  .         /          '.     .     ,     ^ 

Usually  cool 

Warm 

Table  showing  the  changes  produced  in  the  air  by  breathing. 

When  the  air  contains  less  than  one  sixth  oxygen, 
an  animal  cannot  live  in  it,  and  it  cannot  support  the 
burning  in  a  fire.  Air  that  comes  from  the  lungs  can- 


i36 


FOUL   AIR 


not  support  either  life,  or  a  fire.  A  fire  will  often  burn 
brightly  when  a  person  blows  his  breath  upon  it,  but 
this  is  because  he  then  takes  deep  breaths,  and  blows 
the  air  out  before  his  lungs  have  time  to  take  the 
oxygen  from  it. 

Wrap  the  end  of  a  wire  around  a  piece  of  candle. 
Light  the  candle,  and  lower  it  by  the  wire  into  a  jar 

holding  about  a  pint. 
It  will  burn  about  ten 
seconds,  and  will  then 
go  out. 

Take  a  few  deep 
breaths  and  quickly 
blow  the  last  breath 
into  the  jar,  as  if  you 
were  blowing  a  fire. 
A  lighted  candle  will 
now  burn  in  the  jar 
nearly  as  long  as  in 
the  jar  filled  with  pure 
air. 

Take  a  deep  breath, 
hold  it  for  ten  seconds, 
and  blow  it  into  the  jar.  A  lighted  candle  will  then  go 
out  as  soon  as  it  is  lowered  into  the  jar,  for  the  air 
loses  a  large  part  of  its  oxygen  while  it  remains  in  the 
lungs. 

Why  the  Outdoor  Air  stays  Pure.  —  Since  fires  and 
animals  are  always  using  up  oxygen  and  pouring  car- 


Experiment.    Lowering  a  burning  candle 
into  a  jar. 


FOUL  AIR  137 

bon  dioxide  into  the  air,  we  might  suppose  that  the 
outdoor  air  would  finally  become  impure.  It  does  not 
do  so  for  two  reasons:  first,  the  winds  carry  the  im- 
purities away  and  bring  in  fresh  air,  and  second,  plants 
take  carbon  dioxide  from  the  air  and  use  it  as  food. 
Their  green  leaves  separate  the  oxygen  from  the  carbon. 
They  give  the  oxygen  back  to  the  air,  and  use  the  carbon 
in  building  up  their  stems,  roots,  fruit,  and  other  grow- 
ing parts.  The  quantity  of  oxygen  which  plants 
give  to  the  air  nearly  balances  the  amount  of  carbon 
dioxide  which  animals  and  fires  pour  into  the  air. 

Many  persons  suppose  that  plants  growing  in  a  room 
will  purify  the  air.  Plants  really  have  little  effect  on 
the  air  of  a  room.  Probably  the  quantity  of  carbon 
dioxide  and  other  injurious  gases  which  pass  off  from 
the  soil  of  the  flower  pots  is  greater  than  the  amount 
of  oxygen  which  passes  off  from  the  leaves  of  the 
plants. 

Composition  of  Foul  Air.  —  When  a  person  is  in  a 
closed  room,  each  breath  takes  away  some  oxygen  from 
the  air,  and  puts  carbon  dioxide  in  its  place.  Breath- 
ing also  warms 'the  air  and  increases  the  amount  of 
water  and  of  foul-smelling  gases  which  are  in  the  air. 
How  much  the  breathing  will  change  the  air  will  de- 
pend on  how  many  persons  are  in  the  room,  how  long 
they  stay  in  it,  and  how  tightly  the  room  is  closed. 

Effects  of  Foul  Air.  —  When  a  person  breathes  the 
air  of  a  room  over  and  over  again,  he  has  a  headache, 
and  feels  dull  and  short  of  breath.  If  the  air  becomes 


138  FOUL   AIR 

very  foul,  he  feels  dizzy  and  faint.  These  feelings  are 
due  partly  to  the  increased  quantity  of  carbon  dioxide 
in  the  air,  partly  to  the  lack  of  oxygen,  partly  to  foul- 
smelling  substances,  and  partly  to  the  increased  mois- 
ture and  warmth  of  the  air.  But  most  of  the  bad 
effects  which  foul  air  has  upon  the  health  of  the  body 
are  caused  by  the  dust  and  disease  germs  which  are 
usually  found  in  foul  air. 

When  the  air  of  a  schoolroom  begins  to  be  foul,  the 
bad  effects  on  everybody  in  the  room  quickly  appear. 
The  scholars  cannot  put  their  minds  to  their  work,  or 
think  clearly.  Scholars  often  fail  in  their  lessons  be- 
cause they  are  compelled  to  breathe  foul  air  while 
they  study. 

Breathing  foul  air  day  after  day  has  a  bad  effect  on 
the  whole  body.  Many  persons  are  weak,  pale,  and 
sickly,  because  they  breathe  foul  air  during  some  part 
of  the  day  or  night.  Fresh  air,  full  of  oxygen,  and  free 
from  the  poisons  of  the  body,  is  necessary  for  health 
and  strength. 

You  cannot  enjoy  perfect  health  and  strength  unless 
you  always  breathe  fresh  air.  A  few  moments  of 
fresh  air  two  or  three  times  a  day  will  not  be  enough. 
You  need  it  every  moment,  both  night  and  day. 

The  air  of  a  room  begins  to  be  noticeably  foul  when 
the  amount  of  its  carbon  dioxide  is  doubled.  When 
its  carbon  dioxide  is  increased  to  four  or  five  times  the 
amount  that  is  in  outdoor  air,  the  air  is  too  foul  for 
breathing.  The  air  of  crowded  meeting  places  is 


FOUL   AIR  139 

often  so  foul  that  it  contains  ten  or  fifteen  times  as 
much  carbon  dioxide  as  outdoor  air. 

Disease  Germs  in  Foul  Air.  —  If  a  person  has  a  cold, 
or  tonsillitis,  or  diphtheria,  or  other  disease  which  is 
catching,  he  will  expel  disease  germs  with  tiny  drops 
of  saliva  and  mucus  from  his  nose  and  throat  when  he 
coughs,  or  talks,  or  sneezes,  or  blows  his  nose.  The 
drops  quickly  dry,  and  their  germs  rise  with  the  dust  of 
the  room  and  float  in  the  air.  They  may  then  enter 
the  bodies  of  other  persons  with  their  breath.  Millions 
of  germs  fly  off  from  every  dried  collection  of  mucus 
which  is  spit  upon  a  floor  or  pavement. 

Wherever  many  persons  meet  together,  some  one 
who  has  a  cold  or  other  infectious  disease  is  likely  to  be 
in  the  room.  For  this  reason  the  foul  air  of  houses  and 
meeting  places  nearly  always  contains  disease  germs. 
A  common  way  in  which  a  cold,  or  a  sore  throat,  or 
pneumonia,  or  consumption,  is  caught  is  by  breathing 
air  which  has  been  made  foul  by  some  one  who  has  the 
disease. 

Each  pint  of  foul,  dusty  air  of  a  crowded  room  or 
meeting  place  may  contain  fifty  bacteria,  and  many  of 
them  are  likely  to  be  disease  germs.  Less  than  five 
bacteria  may  usually  be  found  in  a  pint  of  outdoor  air 
from  a  dusty  city  street,  but  if  the  day  is  still  and  the 
streets  are  wet,  the  outdoor  air  will  .contain  almost  no 
bacteria  at  all. 

It  is  almost  impossible  for  you  to  catch  a  disease  by 
breathing  outdoor  air.  If  you  keep  a  room  supplied 


140  FOUL   AIR 

with  outdoor  air,  you  will  not  catch  a  cold  or  any  other 
disease  from  the  air,  for  there  will  be  no  disease  germs 
floating  in  it. 

How  to  Tell  Foul  Air.  —  An  easy  way  of  telling 
whether  or  not  the  air  of  a  room  is  foul  is  by  its  smell. 
When  the  amount  of  carbon  dioxide  in  the  air  has  been 
doubled  by  breathing,  there  will  be  enough  waste  mat- 
ters breathed  from  the  lungs  to  give  the  air  an  unpleas- 
ant smell.  An  odor  of  foul  air  that  you  can  notice 
at  all  is  a  sign  that  the  air  is  unfit  to  breathe,  and  that 
it  is  likely  to  contain  disease  germs. 

Some  persons  think  that  the  smell  of  foul  air  comes 
from  dirty  clothes,  or  from  a  dirty  skin.  Dirt  makes  the 
smell  worse,  but  the  greater  part  of  the  odor  comes  from 
the  inside  of  the  body.  Foul  air  in  the  houses  of  per- 
sons who  are  clean  and  educated  has  the  same  smell  as 
foul  air  in  the  houses  of  those  who  are  ignorant  and 
dirty. 

After  breathing  foul  air  for  a  few  moments,  you  may 
become  used  to  the  smell,  and  may  no  longer  notice  it ; 
but  the  air  is  then  as  dangerous  as  ever.  If  you  are  not 
sure  about  the  freshness  of  the  air  of  your  room,  step 
out  of  doors  for  a  moment.  If  you  can  notice  an  un- 
pleasant smell  in  the  air  when  you  come  back  to  the 
room,  the  air  is  foul  and  unfit  for  breathing.  Then 
change  the  air  for  fresh  air  from  out  of  doors. 

Vapor  of  Water  in  Foul  Air.  —  Expired  air  contains 
nearly  all  the  vapor  of  water  that  it  can  hold.  When 
the  air  is  cold,  the  vapor  in  the  breath  looks  like 


FOUL  AIR 


141 


steam.  Air  which  has  been  made  foul  by  breathing 
is  loaded  with  vapor  which  comes  from  the  lungs. 
This  vapor  increases  the  bad  odor  of  the  air  and  the 
unpleasant  feelings  which  are  produced  by  the  foul 
air.  If  the  windows  of  a  crowded  room  are  wet  with 
vapor  which  is  produced  by  breathing,  that  air  is  too 
foul  to  be  breathed  with  safety. 

Reckoning  when  Air  will  become  Foul.  —  If  you 
were  shut  in  a  tightly  closed  room  which  measures  10 
feet  square  and  10  feet  high,  how  long  could  you  re- 
main in  the  room  before  the  air  would  become  unfit 
to  breathe  ? 

The  room  would  contain  1000  cubic  feet  of  air. 
Since  2~^6~o  °f  fresh  air  is  carbon  dioxide,  the  amount 
of  it  in  the  room  would  be  ^f^  of  a  cubic  foot,  or  691 
cubic  inches.  If  another  691  cubic  inches  of  carbon 
dioxide  were  breathed  into  the  room,  the  air  would  be 
noticeably  foul.  Since  you  give  off  about  one  cubic 
inch  of  carbon  dioxide  with  each  quiet  breath,  and 
breathe  about  twenty  times  a  minute,  it  will  take  you 
-6^x  minutes,  or  about  half  an  hour,  to  make  the  air 
unfit  for  use.  The  problem  shows  that  a  person  breath- 
ing quietly  causes  1000  cubic  feet  of  fresh  air  to  be- 
come foul  in  half  an  hour.  It  also  shows  that  each 
person  requires  at  least  2000  cubic  feet  of  fresh  air 
each  hour.  A  person  taking  exercise  will  require  two 
or  three  times  that  quantity  of  fresh  air. 

If  you  should  sleep  in  an  ordinary  bedroom  with 
your  doors  and  windows  closed,  the  air  would  be  unfit 


142  FOUL   AIR 

to  breathe  within  an  hour,  and  in  the  morning  you 
would  wake  up  dull,  and  weak,  and  faint.  If  a  per- 
son who  has  a  cold  should  sleep  in  the  same  room  with 
you,  the  air  would  contain  many  disease  germs  which 
are  given  off  from  his  nose  and  throat  during  the  night, 
and  you  would  be  very  likely  to  catch  the  sickness 
from  him. 

Suppose  a  schoolroom  is  30  feet  square  and  10  feet 
high,  and  has  30  scholars  in  it.  The  quantity  of  air 
will  be  only  300  cubic  feet  for  each  scholar,  and  it  will 
be  unfit  for  breathing  in  less  than  an  hour,  unless  it  is 
changed  for  outdoor  air.  A  single  scholar  who  is 
coughing  and  sneezing  will  soon  give  off  a  dangerous 
number  of  disease  germs  if  the  foul  air  is  allowed  to 
remain  in  the  room. 

QUESTIONS 

Of  what  substances  is  the  outdoor  air  composed  ? 

Of  what  substances  is  expired  air  composed  ? 

Of  what  substances  is  foul  air  composed  ? 

How  much  oxygen  does  a  person  take  from  the  air  with  each 
quiet  breath  ? 

How  much  carbon  dioxide  does  a  person  give  off  with  each 
quiet  breath  ? 

How  much  oxygen  must  there  be  in  the  air  in  order  to  support 
a  man's  life? 

How  can  you  show  that  the  expired  air  of  quiet  breathing 
will  not  support  the  burning  in  a  fire  ? 

What  is  the  difference  between  the  breath  when  a  person 
blows  a  fire,  and  the  expired  breath  of  his  quiet  breathing  ? 


FOUL   AIR 


143 


What  becomes  of  the  impurities  which  are  breathed  into 
outdoor  air  ? 

What  are  the  effects  of  breathing  foul  air  ? 

How  does  foul  air  spread  diseases  ? 

How  can  you  detect  foul  air  ? 

How  can  you  reckon  how  much  fresh  air  a  person  needs  each 
hour? 

If  the  windows  and  doors  of  an  ordinary  bedroom  were 
closed,  how  long  would  the  air  remain  pure  if  one  person  were 
sleeping  in  the  room  ? 

If  no  fresh  air  were  let  into  your  schoolroom  and  if  it  were 
full  of  pupils,  how  long  would  the  air  in  it  remain  fit  for  breath- 
ing? 


CHAPTER  XIV 

VENTILATION 

Need  of  Ventilation.  —  Exchanging  the  impure  air 
of  a  room  for  air  which  is  pure  and  fresh  is  called  ven- 
tilation. A  small  room  will  require  a  complete  change 
of  air  within  an  hour  if  only  one  person  is  in  it.  A 
large  room  will  require  a  complete  change  of  air  within 
a  few  minutes  if  many  persons  are  in  it.  A  school- 
room, church,  or  other  meeting  place  needs  to  be 
ventilated  all  the  time  that  it  is  in  use,  for  the  air  will 
become  unwholesome  within  a  few  moments,  unless  a 
stream  of  fresh  air  is  constantly  flowing  into  it.  Each 
person  requires  at  least  2000  cubic  feet  of  fresh  air 
every  hour  (p.  141). 

How  to  Ventilate.  —  Some  air  will  pass  into  and  out 
of  a  room  through  cracks  in  its  doors,  windows,  floor, 
and  walls.  Well-built  houses  have  few  cracks,  and 
only  a  little  fresh  air  will  enter  them,  unless  openings 
are  made  to  the  outdoor  air. 

One  way  of  ventilating  a  room  is  to  open  a  window. 
This  is  often  the  only  way  to  get  fresh  air  into  a  room. 
It  is  easy  to  ventilate  a  room  that  is  heated.  Warm  air 
is  lighter  than  cold  air,  and  will  rise  to  the  ceiling,  like 
a  cork  on  water.  When  the  upper  sash  of  a  window 

144 


VENTILATION 


145 


is  lowered,  a  stream  of  foul  air  passes  out  above  it. 
Fresh  air  enters  the  room  between  the  two  sashes,  and 
through  cracks  in  the  other  parts  of  the  room.  If  foul 


Diagram  of  ventilation. 

air  passes  out  of  the  room,  we  may  be  sure  that  other 
air  enters  the  room. 

When  the  lower  sash  of  a  window  is  raised,  foul  air 
sometimes  passes  out  through  the  opening,  and  some- 
times fresh  air  blows  into  the  room  through  the  open- 
ing, but  whether  the  foul  air  blows  out,  or  fresh  air 
blows  in,  the  air  of  the  room  becomes  changed. 

Ventilators.  —  Many  houses,  schools,  churches,  and 


GEN.   HYG. 


10 


146  VENTILATION 

other  meeting  places  have  openings  in  the  ceilings 
leading  to  attics,  or  to  large  pipes  which  open  above 
the  roofs  like  chimneys.  These  openings  carry  off 
the  foul  air,  while  fresh,  cool  air  enters  through  the 
doors -and  windows. 

In  large  buildings,  fans  are  often  placed  in  the  base- 
ments to  force  fresh  air  through  the  rooms.  In  this 
way  the  amount  of  air  sent  into  the  room  may  be  reg- 
ulated, and  the  air  of  the  room  may  be  kept  perfectly 
pure. 

Ventilating  Bedrooms.  —  Some  persons  think  that  a 
bedroom  does  not  need  to  be  ventilated  during  the 
night  if  it  is  aired  well  during  the  daytime.  A  person 
sleeping  in  a  small,  closed  bedroom  will  cause  the 
roomful  of  fresh  air  to  become  foul  within  an  hour 
after  he  goes  to  bed.  He  will  then  breathe  foul  air 
through  all  the  rest  of  the  night,  unless  he  ventilates 
the  room. 

Many  su'ppose  that  a  person  will  not  be  harmed  by 
breathing  air  which  he  himself  has  made  foul.  Im- 
pure air  is  as  poisonous  to  the  person  who  makes  it 
foul  as  it  is  to  another  person  who  may  breathe  it. 

The  Arithmetic  of  Ventilation.  —  If  twenty  persons 
are  in  a  room,  how  wide  should  the  windows  be  opened 
in  order  to  keep  the  air  of  the  room  fresh  ? 

The  quantity  of  fresh  air  which  should  enter  the 
room  each  hour  is  at  least  40,000  cubic  feet,  whether 
the  room  is  large  or  small,  for  each  person  needs  2000 
cubic  feet  of  fresh  air  each  hour  (p.  141). 


VENTILATION  147 

A  gentle  current  of  air  that  barely  shakes  a  curtain 
will  move  about  four  feet  a  second,  or  about  as  fast 
as  a  man  walking  rather  slowly.  If  air  flows  at 
that  rate  through  a  window  three  feet  wide,  which  is 
opened  four  inches,  four  cubic  feet  will  pass  through  the 
opening  in  one  second,  240  cubic  feet  in  a  minute,  and 
14,400  cubic  feet  in  an  hour.  Therefore,  three  win- 
dows will  have  to  be  kept  open  four  inches  in  order  to 
supply  the  40,000  cubic  feet  of  air  per  hour  which 
twenty  persons  need.  If  the  air  currents  move  rapidly 
enough  to  make  a  cold  draft  across  the  room,  or  to 
blow  the  curtain  aside,  smaller  openings  may  supply  a 
sufficient  quantity  of  fresh  air.  If  the  outdoor  air  is 
warm  and  still,  larger  openings  will  be  required. 

Drafts.  —  Many  persons  do  not  ventilate  their 
rooms  and  meeting  places  during  cold  weather  because 
they  fear  that  drafts  will  produce  the  forms  of  sickness 
called  colds.  A  cold  is  caused  by  disease  germs  which 
come  from  other  sick  persons,  just  as  measles  come 
from  germs  which  another  person  gives  off  from  his 
body.  If  a  person  gives  off  the  germs  of  a  cold  to  the 
air  of  a  room,  any  one  who  breathes  the  air  will  take 
the  germs  into  his  nose  and  throat,  whether  there  is  a 
draft  in  the  room  or  not.  The  time  to  open  a  window 
and  to  begin  to  ventilate  is  as  soon  as  any  one  comes 
into  a  room,  and  before  the  air  becomes  foul.  If  the 
air  of  a  room  is' pure  and  fresh,  there  will  be  no  disease 
germs  in  it  and  a  person  will  not  catch  a  cold  from 
breathing  the  air. 


148 


VENTILATION 


It  is  nearly  always  possible  to  ventilate  a  room  with- 
out producing  drafts.  One  way  is  to  drop  the  upper 
sashes  of  the  windows  on  the  side  of  the  room  which  is 
opposite  to  that  on  which  the  wind  blows.  The  main 
stream  of  air  will  then  flow  out  of  the  room,  and  fresh 
air  will  enter  in  many  small  streams  through  cracks  in 
the  doors  and  windows. 

Another  way  to  prevent  a  draft  while  ventilating  a 
room  is  to  tack  a  sheet  of  thin  muslin  to  a  frame  and 
place  it  in  an  open  window  as  you  would  a  mosquito 
screen.  This  will  allow  fresh  air  to  enter  the  room, 
but  will  prevent  it  from  blowing  across  the  room 

in  a  draft. 

Dust.  —  Any  kind  of 
dust  is  harmful,  and 
those  persons  who  work 
in  dusty  air  are  more 
likely  to  catch  lung  dis- 
eases than  those  who 
work  in  the  open  air. 
Bronchitis  and  consump- 
tion are  common  among 
tool  grinders,  for  they 
breathe  sharp  particles 
of  steel  which  are  ground 

Dust  as  seen  under  a  microscope.          ,.  tVi     t    ols 

Dust  in  Foul  Air.  —  The  air  of  living  rooms  and 
meeting  places  is  nearly  always  dusty.  The  dust 
consists  of  soil,  ashes,  bits  of  skin  from  the  body,  and 


VENTILATION  149 

shreds  of  wood,  cotton,  and  wool.  These  substances 
may  not  do  a  great  deal  of  harm,  for  the  mucus  of 
the  nose  and  throat  usually  catches  them  and  prevents 
them  from  reaching  the  lungs. 

Bacteria  in  Dust.  —  House  dust  also  contains  many 
kinds  of  bacteria  and  spores  of  molds  (p.  37).  Many 
of  the  bacteria  are  those  which  have  come  from  the 
bodies  of  persons,  and  often  they  are  the  bacteria  of 
diseases.  These  kinds  of  bacteria  are  dangerous,  for 
they  may  multiply  rapidly  in  the  nose,  throat,  and  air 
tubes,  and  produce  diseases  in  those  who  breathe 
them.  One  of  the  principal  reasons  why  foul  air  is 
dangerous  is  that  persons  who  breathe  the  air  stir  up 
dust  and  disease  germs  from  the  floors,  carpets,  and 
furniture.  If  a  room  is  clean,  only  a  little  dust  and 
very  few  bacteria  will  rise  into  the  air.  Keeping  a 
room  well  swept  and  dusted  will  prevent  a  great  deal  of 
sickness. 

Sweeping  and  Dusting.  —  While  you  are  sweeping 
a  room,  open  its  doors  and  windows  so  that  the  dust 
will  be  blown  away.  When  you  dust  the  furniture, 
use  a  moist  cloth  so  that  it  will  hold  the  dust  and  not 
scatter  it  through  the  air  again. 

Sweeping  will  not  remove  all  the  dirt  from  carpets 
which  are  tacked  down  to  the  floor,  for  a  broom  will 
remove  only  the  dirt  which  is  oh  the  surface,  and  will 
not  take  out  the  dirt  and  dust  which  lie  among  the 
threads,  or  under  them.  Rugs  are  more  healthful 
than  carpets,  for  they  may  be  taken  up  and  cleaned. 


150  VENTILATION 

A  vacuum  cleaner  is  an  excellent  thing  for  cleaning 
carpets  and  cushions,  for  the  dirt  and  dust  are  forced 
up  from  among  the  threads,  and  held  in  a  tight  box 
from  which  they  cannot  escape  into  the  air. 

A  floor  which  is  varnished  or  painted  is  hard  and 
smooth,  and  dust  and  dirt  may  be  easily  removed  from 
it.  The  floors  of  schoolrooms  and  other  meeting  places 
are  likely  to  be  worn  and  soiled  by  the  feet  of  many  per- 
sons walking  across  them.  Oil  is  an  excellent  thing 
for  these  floors,  for  it  will  help  to  harden  the  floors  and 
will  prevent  dust  from  rising  from  them. 

Sunshine  in  a  Room.  —  Disease  germs  will  often 
stay  alive  for  days  and  weeks  in  dark,  damp  corners  of 
rooms  and  closets,  but  sunlight  will  dry  a  room,  and 
will  also  kill  the  disease  germs  which  may  be  in  it. 
Sunlight,  cleanliness,  and  fresh  air  are  the  best  of  all 
means  for  making  a  room  healthful. 

Many  old  houses  have  rooms  which  do  not  have  a 
single  window  opening  into  the  outside  air.  These 
rooms  are  breeding  places  of  disease,  for  they  receive 
neither  light,  nor  fresh  air.  Most  cities  now  have  laws 
that  every  room  in  a  house  shall  have  windows  opening 
into  the  outside  air.  There  are  also  laws  that  large 
air  shafts  shall  be  left  open  between  crowded  buildings, 
so  that  every  room  may  get  air  and  light. 


VENTILATION  151 

QUESTIONS 

What  is  ventilation  ? 

How  much  fresh  air  does  each  person  need  in  an  hour  ? 

How  can  you  ventilate  a  room  ? 

How  does  heating  a  room  help  to  ventilate  it  ? 

When  should  you  begin  to  ventilate  a  room  in  which  a  crowd 
gathers  ? 

How  rapidly  may  a  current  of  air  move  through  a  window 
without  making  a  strong  draft  ? 

How  can  you  reckon  how  wide  to  open  the  windows  of  a  room 
in  order  to  ventilate  it  properly  ? 

How  can  you  prevent  a  draft  in  a  room  while  ventilating  it  ? 

Of  what  does  dust  in  houses  consist  ? 

What  harm  may  come  from  breathing  dusty  air  ? 

How  should  you  sweep  and  dust  a  room  ? 

Why  is  a  vacuum  cleaner  an  excellent  machine  to  use  for 
cleaning  a  room  ? 

How  does  painting  a  floor  help  to  make  a  room  healthful  ? 

Why  are  rugs  more  healthful  than  carpets  ? 

How  does  sunshine  help  to  make  a  room  healthful  ? 

Why  do  cities  have  laws  regulating  the  number  of  windows 
in  a  room  ? 


CHAPTER  XV 


BODY  HEAT 

Source  of  Heat  in  the  Body.  - 

The  body  is  warmed  by  the  oxida- 
tion of  its  food  and  flesh.  A  large 
part  of  the  oxidation  takes  place  in 
the  muscles.  Exercise  makes  a 
person  feel  warm,  for  oxidation 
takes  place  rapidly  when  the  mus- 
cles are  in  use  (p.  81).  When  a 
person  sits  still,  oxidation  goes  on 
slowly,  and  he  feels  cool. 

Thermometer.  -  -  The  warmth  of 
an  object  is  called  its  temperature. 
It  may  be  measured  by  means  of 
a  thermometer.  The  kind  of  ther- 
mometer which  is  in  common  use 
consists  of  a  glass  bulb  blown  upon 
the  end  of  a  small  glass  tube,  and 
filled  with  mercury.  Heat  causes 
the  mercury  to  expand  and  rise  in 
the  tube.  The  tube  is  marked  with 

Thermometers  for  taking  . 

the  temperature  of  the    degrees,  and  by  reading  the  mark 


body. 


at  which  the  mercury  stands  we 
152 


BODY   HEAT  153 

can  tell  the  temperature.  The  letter  F.  after  a  degree 
figure  shows  that  the  marking  called  the  Fahrenheit 
scale  is  used.  In  this  scale  a  freezing  temperature  is 
marked  32°,  and  the  temperature  of  boiling  water  212°. 

Temperature  of  the  Body.  —  If  you  should  place  a 
thermometer  in  the  mouth  of  a  healthy  person,  you 
would  find  that  it  shows  a  temperature  of  very  nearly 
98.5°  F.  If  you  should  bury  the  thermometer  in  his 
flesh,  it  would  still  show  nearly  the  same  temperature. 

Some  parts  of  the  body,  such  as  the  ears  and  fingers, 
produce  very  little  heat,  and  yet  they  too  have  a  tem- 
perature of  98.5°  F.,  unless  the  air  is  very  cold.  The 
blood  keeps  the  temperature  of  all  parts  of  the  body  at 
nearly  the  same  degree  of  warmth,  for  its  stream  is  so 
large  and  swift  that  it  warms  the  cooler  parts,  and  cools 
the  warmer  parts. 

Fever.  —  A  body  temperature  which  is  a  degree  or 
more  warmer  than  98. 5°  F.  is  called  a  fever,  and  is  a 
sign  of  sickness.  If  the  temperature  is  101°  F.,  a  person 
usually  feels  sick  and  weak.  If  it  is  104°  F.,  he  is 
dangerously  sick.  A  fever  is  nearly  always  caused  by 
disease  germs  growing  in  the  body. 

Feeling  of  Warmth.  —  You  cannot  always  tell  the 
temperature  of  your  body  by  your  own  feelings  of 
warmth.  This  is  because  most  of  the  nerves  by  which 
you  feel  warmth  are  in  your  skin.  If  your  skin  is  cold, 
you  seem  to  feel  cold  all  through  your  body,  no  matter 
what  the  temperature  of  the  inside  of  your  body  may 
be.  At  the  beginning  of  a  fever  your  skin  will  some- 


154  BODY   HEAT 

times  be  pale  and  cold  from  lack  of  blood.  You  will 
then  feel  cold,  even  though  a  temperature  of  the  inside  of 
your  body  may  be  102°  F.,  or  more.  A  feeling  of  cold 
during  a  fever  is  called  a  chill. 

Regulation  of  Temperature. --The  temperature  of 
your  body  does  not  change  more  than  half  a  degree 
while  you  are  healthy.  If  you  are  well  and  strong,  it 
stays  at  98.5°  F.,  whether  you  feel  too  warm  after 
running,  or  are  shivering  in  a  cold  wind.  The  prin- 
cipal way  in  which  the  body  regulates  its  temperature 
is  by  getting  rid  of  the  heat  which  it  does  not  need. 

A  great  deal  of  the  heat  which  the  body  loses  passes 
into  the  air  which  touches  the  skin,  for  the  air  is  nearly 
always  cooler  than  the  body.  When  a  large  quantity 
of  heat  is  produced,  as  by  hard  exercise,  the  arteries  of 
the  skin  become  large  and  bring  a  great  amount  of 
blood  near  the  cool  air.  On  a  hot  day  the  skin  is  red 
and  full  of  blood,  for  it  is  trying  to  throw  off  heat.  On 
a  cold  day  the  skin  is  pale,  for  its  arteries  contract  and 
keep  the  blood  away  from  the  cold  air  which  would 
cool  the  blood  too  rapidly  (p.  91). 

If  your  hands  are  cold,  you  can  warm  them  by  rub- 
bing or  clapping  them  around  your  back  so  as  to  make 
a  large  quantity  of  warm  blood  flow  through  them. 

Perspiration  and  Heat.  —  On  very  warm  days  and 
in  hot  places,  the  air  may  be  warmer  than  the  skin. 
Still  the  body  does  not  usually  become  warmer  than 
98.5°  F.,  for  the  perspiration  in  drying  takes  the  heat 
away  from  the  body.  The  perspiration  is  the  principal 


BODY   HEAT  155 

means  by  which  the  temperature  of  the  body  is  pre- 
vented from  rising  on  hot  days,  and  during  hard  exer- 
cise. 

Sunstroke.  —  If  blood  does  not  flow  freely  through 
the  skin  on  a  hot  day,  a  person  may  not  perspire,  and 
then  his  body  may  become  too  warm.  The  heat  may 
make  him  weak,  and  we'then  say  that  he  has  a  sun- 
stroke. 

When  a  person  has  a  sunstroke,  his  skin  may  be  pale 
and  cold,  but  the  inside  of  his  body  will  be  too  warm. 
Lay  him  down  in  a  cool  place,  and  rub  his  skin  with  cold 
water.  This  will  make  the  blood  flow  through  the 
skin,  and  will  cool  the  body. 

Clothing.  —  Heat  passes  off  from  the  body  very 
rapidly  when  the  air  is  cold.  If  the  temperature  of  the 
air  is  below  70°  F.,  clothes  will  be  needed  in  order  to 
prevent  the  heat  from  passing  off  too  rapidly.  Clothes 
do  not  make  heat.  They  keep  the  body  warm  by  pre- 
venting the  air  from  taking  heat  away  from  the  skin. 
If  the  temperature  of  the  air  is  70°  F.,  or  warmer,  the 
body  can  regulate  its  own  temperature  without  the 
help  of  clothes. 

If  the  layers  of  cloth  in  a  suit  of  clothes  were  pressed 
into  a  firm  sheet,  they  would  not  keep  the  body  warm, 
for  they  would  allow  the  heat  to  pass  through  them 
readily.  But  if  they  are  made  up  of  loose  fibers  and 
layers,  the  air  which  is  in  them  prevents  the  heat  from 
passing  off.  For  this  reason  a  number,  of  thin  gar- 
ments are  warmer  than  a  single  thick  one  ;  cloth  which 


156  BODY  HEAT 

is  soft  and  loosely  woven  is  warmer  than  that  which 
is  hard  and  tightly  woven ;  and  garments  which  fit 
loosely  are  warmer  than  those  which  fit  tightly. 

Woolen  cloth  is  warm  because  it  is  usually  soft  and 
loosely  woven.  Cotton  or  linen  cloth  which  is  soft 
and  loosely  woven  is  nearly  as  warm  as  wool,  but 
when  it  is  washed,  it  of  ten '  becomes  hard  and  firm. 
It  does  not  then  protect  the  body  from  the  cold  so 
well  as  woolen  cloth. 

Wet  Clothing.  —  If  clothes  are  wet,  the  heat  of  the 
body  causes  the  water  to  dry  from  them.  The  vapor 
then  takes  away  the  heat  and  makes  the  body 
feel  cold.  Damp  clothes  are  harmful  when  they 
cool  the  body.  They  will  not  usually  harm  the  body 
during  exercise,  for  the  exercise  will  keep  the  body 
warm.  They  are  harmful -when  a  person  sits  still, 
for  they  may  then  cool  the  body  more  rapidly  than 
heat  is  produced. 

Taking  Cold.  —  It  used  to  be  supposed  that  cold- 
ness was  the  cause  of  the  kinds  of  sickness  which  are 
called  colds.  We  know  that  colds  are  caused  by  dis- 
ease germs  which  come  from  foul  air,  and  from  dust  and 
dirt.  There  are  no  more  disease  germs  in  air  which  is 
cold  and  damp  than  in  air  which  is  warm  and  dry. 
On  days  which  are  cold  or  damp  people  keep  their  doors 
and  windows  closed,  and  the  air  of  their  houses  becomes 
foul  and  full  of  disease  germs  (p.  139).  They  then 
catch  cold  by  breathing  the  foul  air  when  they  go  into 
the  house  to  warm  and  dry  themselves.  Coldness 


BODY   HEAT  157 

and  chills  will  not  make  a  person  take  cold  unless  he 
also  takes  living  germs  of  the  sickness  into  his  body. 

There  is  a  way  in  which  coldness  may  help  a  person 
to  catch  cold  when  he  takes  disease  germs  into  his 
body.  Cold  air  blowing  upon  the  body  may  weaken 
it  so  much  that  the  white  blood  cells  cannot  destroy 
disease  germs  when  they  enter  the  body  (p.  90).  If 
the  body  is  chilled,  it  may  not  be  able  to  destroy 
disease  germs  which  it  is  usually  able  to  overcome. 
But  there  must  be  disease  germs  in  the  body  before  a 
cold  can  develop.  Remember  also  that  disease  germs 
in  the  body  may  cause  a  cold  whether  the  body  has 
been  chilled  or  not. 

Heating  Houses.  —  The  body  can  regulate  its  heat 
so  that  a  person  can  live  in  air  which  is  either  colder 
than  freezing,  or  warmer  than  the  body  itself.  But 
it  can  regulate  its  heat  most  easily  when  the  tempera- 
ture of  the  air  is  about  halfway  between  freezing  and 
body  heat.  This  temperature  is  from  65°  F.  to  70°  F., 
and  is  the  most  healthful  temperature  for  a  living 
room  in  winter.  If  living  rooms  are  heated  warmer 
than  70°  F.,  the  air  usually  feels  too  warm,  and  if  they 
are  cooler  than  65°  F.,  the  air  usually  feels  chilly. 

It  would  be  easy  to  heat  a  house  if  the  same  air 
could  be  kept  in  it  hour  after  hour.  But  if  a  room  is 
properly  ventilated  on  a  cold  day,  the  steady  stream 
of  outdoor  air  which  flows  into  the  building  will  have 
to  be  heated.  Many  persons  do  not  ventilate  their 
houses  in  winter  because  ventilation  cools  their  rooms. 


158  BODY   HEAT 

Yet  the  sickness  caused  by  the  foul  air  usually  costs 
much  more  than  the  wood  and  coal  which  are  saved 
by  not  ventilating  the  rooms. 

Methods  of  Heating.  —  A  fireplace  is  a  healthful 
form  of  heater,  for  the  draft  of  the  chimney  carries 
away  a  great  deal  of  foul  air  from  the  room.  But  a 
fireplace  wastes  a  great  deal  of  the  heat. 

A  stove  supplies  heat  cheaply,  for  it  gives  its  heat 
directly  to  the  air  of  the  room.  But  it  does  not  venti- 
late the  room,  for  it  carries  away  very  little  of  the  foul 
air. 

The  hot-air  furnace  in  the  cellar  is  a  popular  form  of 
heater.  It  sends  the  heat  through  the  house  by  means 
of  a  stream  of  heated  air.  Furnaces  which  send  the 
heat  to  the  rooms  by  means  of  steam  or  hot  water  are 
economical,  but  they  do  not  ventilate  the  rooms. 

Stoves  which  burn  oil  or  gas  are  sometimes  used  to 
heat  rooms,  but  they  are  unhealthful,  for  most  of  them 
pour  their  burned  gases  into  the  air,  and  make  it  foul. 

Moisture  in  Heated  Air.  —  Air  always  contains 
some  vapor  of  water.  Air  at  a  temperature  of  70°  F. 
can  hold  over  three  times  as  much  vapor  as  air  at  a 
freezing  temperature.  Damp  air  which  is  freezing 
cold  becomes  very  dry  air  when  it  is  heated.  The 
heat  does  not  take  away  any  of  the  vapor  from  the  air, 
but  it  makes  the  air  able  to  carry  a  great  deal  more 
vapor  than  cold  air  can  carry. 

In  cold  weather  the  heated  air  of  houses  is  usually 
too  dry,  and  takes  water  from  every  moist  thing  which 


BODY   HEAT  159 

it  touches.  It  takes  moisture  from  the  skin,  nose,  and 
throat,  and  makes  them  tender  and  unable  to  resist 
the  growth  of  disease  germs  which  may  fall  upon  them. 
Dry,  heated  air  is  as  harmful  as  a  draft  of  cold  air. 

Dry,  warm  air  also  dries  the  perspiration  from  the 
skin  rapidly,  and  makes  the  body  feel  cold.  If  the 
air  is  moist,  it  cannot  take  away  the  perspiration 
rapidly.  Moist  air  at  a  temperature  of  65°  F.  feels 
warmer  than  dry  air  at  70°  F.  You  can  save  both 
heat  and  health  by  keeping  a  pan  of  hot  water  on  the 
stove,  or  register,  or  radiator,  or  by  keeping  the  water 
tank  of  the  furnace  filled,  if  a  hot-air  heater  is  used. 

Lighting  a  Room.  —  Lights  which  are  produced  by 
burning  use  up  oxygen  and  make  the  air  foul,  just  as 
breathing  does.  A  candle  uses  about  as  much  of  oxy- 
gen as  a  man.  A  bright  light  made  by  burning  kero- 
sene or  gas  uses  about  as  much  oxygen  as  five  or  ten 
men.  Electric  lights  do  not  use  up  oxygen  or  make 
the  air  foul  at  all,  for  their  light  comes  from  white 
hot  wires  which  lie  inside  of  air-tight  glass  bulbs. 
Electric  lights  are  usually  the  most  healthful  of  all  the 
means  of  lighting  houses. 

Coal  Gas  Poisoning.  —  A  coal  stove  burning  with  a 
poor  draft  often  gives  off  a  gas,  called  carbon  monoxide. 
This  substance  is  very  poisonous,  for  when  it  is  breathed, 
it  unites  with  the  red  blood  cells,  and  prevents  them 
from  carrying  oxygen  through  the  body.  This  same 
substance  is  one  of  the  principal  things  in  illuminating 
gas.  We  can  tell  it  by  its  smell.  If  there  is  the  least 


160  BODY   HEAT 

smell  of  carbon  monoxide  in  a  room,  the  air  is  dangerous 
for  breathing. 

Weather.  —  Some  persons  think  that  during  bad 
weather,  the  outdoor  air  contains  something  which  is 
likely  to  make  them  sick,  and  so  they  shut  the  air 
out  of  their  houses  on  unpleasant  days.  Most  of  the 
diseases  which  these  persons  fear  are  caused  by  disease 
germs  in  the  foul  air  of  their  houses  and  meeting  places, 
and  not  by  outdoor  air  at  all.  Weather  and  climate 
are  due  principally  to  four  conditions  of  the  outdoor 
air:  i,  temperature;  2,  motion,  or  the  wind;  3,  damp- 
ness, such  as  rain  and  fog ;  4,  sunshine.  Nearly  all 
,the  unhealthful  effects  of  bad  weather  are  caused  by 
changes  in  the  temperature  of  the  body.  If  the  weather 
is  unpleasant,  you  can  protect  yourself  with  your 
clothes  and  houses. 

Alcohol  and  Body  Heat.  —  Alcohol  is  easily  oxidized 
in  the  body,  and  produces  a  large  quantity  of  heat 
soon  after  a  person  takes  it  (p.  132).  But  the  body 
tries  to  get  rid  of  the  extra  amount  of  heat  by  causing 
the  arteries  of  the  skin  to  expand  (p.  103).  The 
large  quantity  of  blood  which  flows  through  the  skin 
gives  a  feeling  of  warmth,  but  the  heat  is  on  the  sur- 
face, and  soon  passes  off.  Alcohol  cools  the  body  in- 
stead of  warming  it.  Those  who  travel  in  arctic  lands 
find  that,  when  they  do  not  use  alcohol,  they  can  en- 
dure cold  much  better  than  when  they  use  it. 


BODY   HEAT  161 

QUESTIONS 

What  produces  the  heat  of  the  body  ? 

What  is  a  thermometer? 

What  is  the  natural  temperature  of  the  body  ? 

What  is  a  fever  ? 

What  is  the  usual  cause  of  fever  ? 

What  is  the  cause  of  the  chilly  feeling  which  is  often  present 
at  the  beginning  of  a  fever  ? 

In  what  two  principal  ways  does  heat  pass  off  from  the 
body? 

How  does  the  blood  flowing  through  the  skin  help  to  regulate 
the  temperature  of  the  body  ? 

How  does  the  perspiration  help  to  regulate  the  temperature 
of  the  body  ? 

What  is  a  sunstroke  ?  What  may  be  done  to  help  a  person 
who  has  a  sunstroke  ? 

How  do  clothes  keep  the  body  warm  ? 

How  may  cotton  cloth  be  made  as  warm  as  woolen  ? 

Why  do  wet  clothes  feel  cool  ? 

In  what  way  does  cold,  damp  weather  help  people  to  take 
cold? 

How  may  a  draft  of  cold  air  help  to  cause  a  cold  ? 

What  is  the  most  comfortable  temperature  for  a  living  room  ? 

Why  is  a  fireplace  a  healthful  form  of  heater  ? 

Why  is  the  air  of  a  heated  room  usually  drier  than  the  air 
out  of  doors  ? 

Why  is  dry  air  in  a  heated  room  harmful  ? 

Why  are  electric  lights  a  more  healthful  form  of  lighting  a 
room  than  lights  produced  by  burning  kerosene  or  gas  ? 

What  is  the  danger  from  breathing  coal  gas  ? 

In  what  way  do  changes  in  the  weather  harm  the  body  ? 

What  effect  does  alcohol  have  on  the  temperature  of  the 
body? 

GEN.    HYG. —  II 


CHAPTER  XVI 


THE  SKIN 

Structure  of  the  Skin.  -  -  The  skin  consists  of  a  thick 
network  of  connective  tissue  fibers,  called  the  dermis, 
or  true  skin,  which  is  covered 
with  a  thin  sheet  of  epithelial 
cells,  called  the  epidermis  (p.  24). 
When  the  dermis  of  an  animal's 
skin  is  hardened  by  tanning,  it 
forms  leather.  The  connective 
tissue  in  the  dermis  of  a  person's 
skin  looks  like  the  fibers  of  fine 
leather. 

The  color  of  the  skin  is  due 
partly  to  the  red  color  of  the 
blood  in  the  skin,  and  partly  to  a 
thin  layer  of  colored  cells  in  the 
deep  part  of  the  epidermis.  These 
cells  become  colored  brown,  or 
tanned,  when  a  person  is  exposed 
to  the  sunshine  a  great  deal. 
Their  use  is  to  act  as  a  curtain 


A  sweat  gland. 
Magnified. 


and  protect  the  skin  from  being  burned  by  the  rays 
of  the  sun. 

162 


THE   SKIN  163 

The  Epidermis.  — The  epidermis  consists  of  several 
layers  of  flat  epithelial  cells,  which  are  like  soft  scales 
(p.  22).  The  cells  are  formed  next  to  the  dermis, 
and  as  they  grow,  they  are  pushed  away  by  other  cells 
which  grow  beneath  them.  The  older  cells  become 
dry  and  loosened,  and  are  finally  worn  away.  The 
whole  epidermis  is  shed  about . once  a  month.  If  the 
cells  were  not  worn  away  from  the  surface,  the  epider- 
mis would  become  an  inch  or  more  in  thickness. 

The  epidermis  contains  no  blood  tubes  or  nerves, 
and  so  it  may  be  cut  or  pricked  without  pain.  It  is 
strong  enough  to  protect  the  blood  tubes  and  nerves 
of  the  dermis  from  injury,  and  yet  it  is  so  thin  that  it 
does  not  interfere  with  cooling  the  blood,  or  with  the 
feeling  of  touch. 

The  epidermis  is  waterproof,  and  prevents  liquids 
and  other  substances  from  passing  into  the  true  skin. 
For  this  reason  a  person  can  handle  poisons  and  disease 
germs  without  danger.  When  medicines  are  given 
with  a  hypodermic  syringe,  a  hollow  needle  is  thrust 
through  the  epidermis  and  the  drug  is  forced  through 
it  into  the  flesh. 

The  waterproof  epidermis  also  prevents  lymph  from 
escaping  from  among  the  cells  of  the  flesh  (p.  99). 
As  a  wound  upon  the  skin  heals,  new  cells  of  epidermis 
grow  over  the  spot.  When  the  epidermis  is  loosened 
from  the  dermis,  as  by  scalding  or  hard  rubbing,  the 
lymph  collects  under  the  loosened  part,  and  forms  a 
bag  of  liquid,  called  a  blister. 


1 64 


THE   SKIN 


Finger  Prints.  —  The  surface  of  the  dermis  is  covered 
with  pointed  projections,    called    papilla,    in    which 
nerves  of  feeling  end.     The  papillae  on  the  balls  of  the 
fingers  and  palms  of  the  hands  form  ridges  and  lines 
which  appear  as  spiral  patterns  upon 
the  surface  of  the  skin. 

Press  the  ball  of  your  forefinger 
upon  an  inking  pad,  such  as  is  used 
for  rubber  stamps,  and  then  make  a 
print  of  the  finger  upon  white  paper. 
An  exact  print  of  the  ridges  will  be 
left  upon  the  paper. 

The  pattern  of  the  lines  on  a 
person's  finger  remains  the  same 
through  life,  and  is  different  from 
the  patterns  on  all  other  persons. 
A  person  may  be  distinguished  by 
his  finger  print  more  surely  than  by 
any  other  means.  The  finger  prints  of  prisoners  are 
taken  and  preserved  in  order  that  the  criminals  may 
be  known  if  they  should  be  arrested  again. 

Perspiration.  —  If  the  skin  is  touched  to  a  clean 
piece  of  cold  glass,  vapor  of  water  will  pass  off  from  it 
and  will  form  a  spot  upon  the  glass.  This  water  is 
the  perspiration,  or  sweat.  It  is  formed  in  deep  glands, 
and  is  discharged  from  the  skin  through  openings  which 
are  sometimes  called  pores  (p.  24). 

The  principal  effect  of  perspiration  is  to  cool  the 
body  (p.  154).'  It  also  helps  to  carry  away  waste 


Finger  prints. 


THE   SKIN 


165 


matters.     About  a  pint  of  perspiration  is  formed  each 
day  whether  the  weather  is  warm  or  cold,  but  on  a  hot 
day  over  a  gallon  may  be 
formed  if  hard  exercise  is 
taken. 

The  Complexion.  - 
Harmful  waste  matters  in 
the  blood  often  cause  the 
skin  to  have  a  rough  and 
muddy  look.  Powders  and 
paints  may  cover  up  the 
skin,  but  they  do  not 
make  it  fair.  The  only 
way  to  get  a  beautiful 
complexion  is  to  live  in 
such  a  way  that  the  waste 
matters  of  the  body  will 
be  of  a  harmless  kind,  and 


Outlet  of  a  sweat  gland  extending 
through  the  epidermis. 


such    as    may    easily    be 
thrown  off  from  the  body. 

Dirt  on  the  Skin.  —  When  perspiration  dries  from 
the  body,  the  substances  which  are  dissolved  in  it  are 
left  as  dirt  on  the  skin.  Other  dirt  on  the  skin  consists 
of  dead  scales  of  epidermis,  and  of  dust  and  bacteria 
from  the  air.  Bacteria  of  decay  often  grow  in  the  dirt 
and  in  the  mouths  of  the  sweat  glands,  and  give  the 
skin  a  bad  odor.  The  disease  germs  which  cause 
wounds  to  become  red  and  sore  often  grow  on  a  dirty 
skin,  and  enter  the  body  when  the  skin  is  wounded. 


i66  THE   SKIN 

Disease  Germs  on  the  Skin.  -  -  The  dirt  and  dust 
which  are  on  the  skin  often  contain  disease  germs  which 
would  cause  sickness  if  they  should  enter  the  mouth. 
Many  persons  catch  typhoid  fever,  diphtheria,  or  other 
diseases  by  touching  their  mouths  or  food  with  hands 
which  are  soiled  with  dirt  containing  the  germs  of  the 
disease.  A  dirty  skin  is  unpleasant,  and  is  also  dan- 
gerous to  health,  for  dirf  and  an  odor  on  the  skin  are 
signs  that  disease  germs  also  are  there. 

Cleanliness.  --The  reason  for  cleansing  the  skin  is 
to  get  rid  of  three  things:  first,  dirt,  which  looks  bad ; 
second,  an  odor,  which  smells  bad ;  and  third,  disease 
germs.  These  three  things  usually  go  together.  A 
skin  that  is  clean  and  has  no  odor  is  almost  free  from 
disease  germs. 

Bathing.  —  The  loosened  shreds  of  epidermis  which 
naturally  peel  from  the  skin  carry  a  great  deal  of  dirt 
with  them.  Rubbing  the  skin  with  the  hands,  or  with 
a  dry  towel,  will  remove  much  of  the  loose  epidermis, 
and  will  help  to  cleanse  the  skin.  But  the  only  way  to 
keep  the  skin  clean  and  free  from  odor  and  disease 
germs  is  to  bathe  the  whole  body  with  water. 

Your  skin  will  have  an  odor  of  dirt  and  perspiration 
unless  you  take  a  warm  bath  with  soap  and  water  at 
least  once  a  week.  A  bathroom  is  one  of  the  most 
important  and  useful  of  all  the  rooms  in  a  house,  for  it 
makes  bathing  easy  and  pleasant. 

Many  cities  support  public  baths.  In  many  large 
factories  there  are  bathrooms  and  warm  water,  for  the 


THE   SKIN  167 

owners  find  that  bathing  improves  the  comfort  and 
health  of  the  workmen,  and  enables  them  to  do  better 
work. 

Bathing  for  Refreshment.  —  A  hot  bath  will  cause 
the  arteries  of  the  skin  to  become  large.  When  a  large 
quantity  of  blood  flows  through  the  skin,  the  amount 
which  flows  through  the  head  and  the  organs  within 
the  body  will  be  lessened.  A  hot  bath  is  useful  in 
making  a  person  feel  quiet  and  restful  after  he  has  been 
studying  or  thinking  hard,  for  it  causes  the  blood  to 
flow  away  from  the  head.  The  best  time  to  take  it 
is  at  night  just  before  bedtime. 

Cold  Baths.  —  A  cold  bath  will  cause  the  arteries 
to  contract,  and  will  force  the  blood  away  from  the 
skin  and  into  the  head  and  internal  organs.  Thus 
it  will  rouse  a  person  and  make  him  feel  active  and 
ready  for  work.  The  best  time  to  take  a  cold  bath  is 
in  the  morning  on  getting  up.  Athletes  and  other 
strong  persons  will  be  helped  by  a  cold  bath,  but ) weak 
and  sickly  persons  are  likely  to  be  harmed  by  a  bath 
which  chills  their  bodies. 

Congestion  and  Hot  Water.  —  When  any  part  of 
the  body  contains  too  much  blood,  we  say  that  it  is 
congested.  A  draft  of  cold  air  blowing  upon  the  neck, 
or  arm,  or  leg  may  cause  the  arteries  of  the  skin  of  that 
part  to  contract.  The  blood  which  is  intended  for  the 
skin  may  then  flow  into  the  muscles  under  the  cold 
skin,  and  may  cause  them  to  become  congested  and 
painful.  Many  of  the  pains  which  are  called  rheumatic 


1 68  THE   SKIN 

pains  are  due  to  the  cooling  of  one  part  of  the  skin 
more  than -another. 

Heating  the  skin  over  a  painful  part  will  often  re- 
lieve the  pain  by  causing  the  blood  to  flow  into  the 
skin.  One  of  the  best  ways  for  applying  the  heat 
is  to  put  a  hot-water  bag  over  the  painful  spot. 
Another  way  is  to  wrap  it  in  a  blanket  or  cloth  wrung 
out  of  hot  water. 

JClean  Clothing.  —  Clothing  becomes  soiled  by  sub- 
stances which  are  rubbed  from  the  skin.  Under- 
clothes which  have  been  worn  for  a  week  will  contain 
the  same  kinds  of  dirt  and  disease  germs  that  were  on 
the  skin.  Soiled  clothing  is  dangerous  to  health. 

Clothes  which  have  been  well  washed  and  ironed 
are  free  from  disease  germs  and  dirt.  The  washing 
removes  most  of  the  germs,  and  those  which  remain 
are  killed  by  the  heat  during  the  ironing.  If  the  clothes 
are  then  handled  with  clean  hands  and  are  stored  in  a 
clean  place,  they  will  remain  clean  and  healthful. 

Hair.  —  Hairs  are  found  on  nearly  every  part  of  the 
body.  They  grow  from  roots  deep  in  the  skin,  and 
are  formed  by  the  matting  together  of  epithelial  cells, 
like  those  of  the  epidermis.  Medicine  rubbed  on  the 
surface  of  the  skin  cannot  reach  the  roots  and  make 
the  hair  grow. 

Hair  roots  are  set  slanting  in  the  skin,  but  they  may 
be  pulled  upright  by  muscles.  When  the  muscles 
contract,  they  pull  the  roots  up  and  the  skin  down,  thus 
producing  the  roughness  of  the  skin  called  goose  flesh. 


THE   SKIN 


169 


This  roughness  may  often  be  seen  when  the  skin  is 
cold. 

Each  hair  root  has  a  gland,  called  a  sebaceous  gland, 
which  forms  an  oil.  The  oil  keeps  the  hair  and  skin 
soft,  and  helps  to  make  the  skin  waterproof. 


Section  of  skin  :  a,  hair  root;  b,  muscle;  c,  oil  gland;  d,  epidermis. 

Care  of  the  Hair.  --The  hair  of  the  head  catches  a 
great  deal  of  dust  which  may  contain  disease  germs. 
The  dirt  may  be  rubbed  upon  a  pillow  during  sleep, 
and  the  disease  germs  may  then  enter  the  nose  and 
produce  a  disease.  Combing  and  brushing  the  hair 
removes  the  dirt  and  disease  germs  and  helps  to  keep 
a  person  healthy.  The  scalp  and  the  hair  need  a  bath 
in  soap  suds  every  week  or  two. 


i  yo 


THE   SKIN 


Washing  the  hair  will  help  to  prevent  the  scales 
called  dandruff.  These  scales  consist  of  bits  of  epi- 
dermis, and  are  often  caused  by  disease  germs  which 
are  spread  from  one  person  to  another  by  combs  and 
brushes.  Use  only  your  own  comb  and  brush,  and 
carry  them  with  you  when  you  go  traveling. 

Pimples.  —  If  a  hair  root  is  unhealthy,  disease  germs 
may  grow  in  it,  or  in  its  oil  glands,  and  produce  a  small 
collection  of  pus,  called  a  pimple,  or  boil.  Every 
pimple  and  boil  has  a  hair  in  the  center  from  which  it 
starts. 

Pimples  and  boils  will  seldom  form  if  a  person  is 
healthy  and  well.  But  if  a  great  deal  of  waste  matter 
is  circulating  in  the  blood,  the  cells  of  the  epidermis 

may  be  unable  to 
prevent  disease 
germs  from  entering 
the  flesh.  One  of  the 
best  preventives  of 
pimples  is  to  eat, 
drink,  and  exercise 
properly,  so  that  the 
waste  substances  of 
the  body  will  be  as 
slightly  poisonous  as 
possible  (p.  33). 

Nails.  —  The  nails 
on    the    fingers    and 
toes   are  composed  of   hardened   cells  of   epidermis. 


Cutting  off  a  hangnail. 


THE   SKIN  171 

They  are  not  poisonous,  but  the  dirt  which  collects 
under  them  often  contains  dangerous  kinds  of  disease 
germs,  for  it  is  composed  of  nearly  every  kind  of  dirt 
which  is  touched.  Dirty  finger  nails  are  both  untidy 
and  dangerous.  They  have  often  been  the  cause  of 
sickness  by  carrying  disease  germs  to  food,  or  into  the 
nose  and  eyes,  or  into  slight  scratches  on  the  skin. 
Keep  your  finger  nails  clean  in  order  to  prevent  the 
spread  of  disease  germs  from  them. 

A  hangnail  is  a  sliver  of  epidermis  which  has  been 
torn  from  the  skin  just  behind  the  nail.  Do  not  tear 
it  off  or  bite  it,  but  cut  it  off  close  to  the  skin  with  a 
sharp  knife. 

QUESTIONS 

Of  what  is  the  dermis  composed  ? 
Of  what  is  the  epidermis  composed  ? 
To  what  is  the  color  of  the  skin  due  ? 
Of  what  use  to  the  skin  is  the  coloring  matter  called  .tan  ? 
What  are  some  of  the  uses  of  the  epidermis  ? 
How  is  a  blister  formed  ? 

What  is  a  common  cause  of  a  poor  complexion  ? 
What  is  the  perspiration? 
What  are  the  uses  of  the  perspiration  ? 
Of  what  does  the  dirt  on  the  skin  consist  ? 
Where  do  disease  germs  on  the  skin  come  from  ? 
Give  some  reasons  for  keeping  the  skin  clean. 
How  often  does  the  whole  body  need  a  bath  ? 
What  effect  does  a  hot  bath  have  on  the  body  ?     When  should 
it  be  taken  ? 

What  is  congestion? 


172  THE   SKIN 

How  does  a  hot- water  bottle  help  congestion  ? 

Give  some  reasons  for  washing  clothes. 

Describe  a  hair  root. 

What  is  the  cause  of  goose  flesh  ? 

Give  some  reasons  for  keeping  the  hair  clean. 

How  may  dandruff  be  prevented  ? 

What  is  the  cause  of  pimples  ? 

How  may  pimples  be  prevented  ? 

In  what  way  are  dirty  finger  nails  dangerous  to  health  ? 

How  may  a  hangnail  be  cured  ? 


CHAPTER  XVII 
EXCRETION 

The  Waste  Matters  of  the  Body.  —  Life  is  supported 
by  the  water,  minerals,  protein,  fat,  sugar,  and  oxygen 
which  are  taken  into  the  body.  After  the  oxygen  has 
united  with  the  other  substances,  they  all  become 
waste  matters  which  the  body  throws  off.  These 
useless  substances  are  called  excretions. 

The  principal  excretions  are  carbon  dioxide,  urea, 
minerals,  and  water  (p.  32).  All  these,  except  water, 
are  somewhat  poisonous,  but  small  quantities  of  waste 
substances  which  are  very  much  more  poisonous  are 
formed  when  the  oxidation  in  the  body  is  disturbed. 

The  principal  organs  of  excretion  are  the  lungs,  the 
kidneys,  the  skin,  and  the  intestine. 

Excretion  by  the  Lungs.  —  About  a  pound  of  carbon 
dioxide  is  produced  in  the  body  each  day,  and  nearly 
all  of  it  passes  off  through  the  lungs,  but  a  little  also 
passes  off  through  the  other  organs  of  excretion.  The 
lungs  also  give  off  about  a  pint  of  water  each  day  in 
the  form  of  vapor  in  the  breath. 

The  Kidneys.  -  -  The  greater  part  of  the  urea  and 
waste  minerals  of  the  body  are  excreted  by  two  organs, 
called  the  kidneys,  which  lie  on  opposite  sides  of  the 

173 


EXCRETION 


backbone  just  behind  the  lowest  ribs.     Persons  who 
have  a  backache  often  suppose  that  the  pain  is  in  the 

kidneys.  This  is  hardly 
ever  so,  but  the  pain  is 
nearly  always  in  the 
muscles  of  the  back. 

The  kidneys  are  glands 
whose  tubes  are  com- 
posed of  cells  of  epi- 
thelium (p.  24).  The 
cells  take  waste  matter 
and  water  from  the  blood, 
and  produce  a  mixture, 
called  the  urine,  which 
they  send  into  a  bag, 
called  the  bladder. 
The  Bladder,  —  The  bladder  lies  in  the  lowest  part 
of  the  trunk  of  the  body.  Its  use  is  to  receive  urine 
from  the  kidneys,  which  produce  it  during  every  mo- 
ment of  the  day  and  night.  It  is  made  of  muscle  and 
holds  about  half  a  pint.  About  three  pints  of  urine 
are  formed  in  each  twenty-four  hours,  and  so  the 
bladder  needs  to  be  emptied  at  least  six  times  a  day. 

Excretion  by  the  Skin.  —  The  glands  of  the  skin  give 
off  a  little  urea  and  minerals,  and  a  great  deal  of  water 
(p.  24).  The  mixture  of  these  substances  is  the 
perspiration  or  sweat.  The  minerals  give  it  a  salt 
taste. 

The  kidneys  give  off  about  ten  times  as  much  waste 


A  kidney  cut  in  two. 


EXCRETION  175 

matter  as  the  skin,  but  when  they  are  diseased,  the 
work  of  the  skin  is  of  great  importance  in  helping  to 
get  rid  of  the  waste  substances  which  the  kidneys  are 
then  unable  to  throw  off. 

Excretion  by  the  Intestine.  —  The  intestine  also 
excretes  waste  matter.  Some  of  the  waste  matter 
consists  of  bile  and  other  substances  which  are  taken 
from  the  blood,  and  some  is  undigested  food. 

Drinking  Water  and  Excretion.  —  Drinking  a  great 
deal  of  water  helps  the  kidneys  and  skin  to  get  rid  of 
waste  matters,  for  the  water  dissolves  the  urea  and 
other  substances,  and  washes  them  away  from  the 
body.  Some  of  these  waste  substances  do  not  dissolve 
readily  in  water,  and  so  a  great  deal  of  water  is  re- 
quired to  wash  them  away.  If  enough  water  is  not 
taken,  the  waste  matters  often  harm  the  kidneys,  and 
produce  Bright's  disease  and  other  forms  of  kidney 
trouble. 

The  natural  quantity  of  water  which  passes  off  from 
the  lungs,  skin,  and  kidneys  each  day  is  about  six 
pints.  About  two  pints  of  water  are  taken  with  food, 
and  so  a  person  needs  to  drink  about  four  pints  of 
liquid  each  day.  This  is  about  equal  to  two  large  cup- 
fuls  of  water,  or  tea,  or  coffee,  or  milk,  three  times  a 
day. 

Alcohol  and  Excretion.  —  When  alcohol  is  taken  into 
the  body,  it  uses  oxygen  which  should  go  to  the  cells 
and  the  food  (p.  132).  The  waste  substances  of 
the  body  are  then  only  half  oxidized,  and  are  much 


176  EXCRETION 

more  harmful  than  the  natural  wastes.  These  poison- 
ous wastes  often  produce  diseases  of  the  kidneys  and 
skin.  One  of  the  most  common  causes  of  kidney 
diseases  is  alcohol. 

Disease  Germs  in  the  Excretions.  —  When  a  person 
has  an  infectious  disease,  many  of  the  disease  germs 
pass  off  from  the  body  with  the  excretions  of  the  intes- 
tine and  kidneys.  They  are  also  found  in  the  mucus 
and  phlegm  of  the  nose  and  throat.  Very  few  of  the 
germs  pass  off  from  the  skin  unless  it  is  diseased,  but 
they  may  often  be  found  on  the  skin  when  it  is  soiled 
by  the  excretions.  The  water  in  which  the  sick  person 
has  washed  or  bathed  will  usually  contain  disease 
germs. 

Disposal  of  Excretions  in  the  Country.  —  One  of  the 
easiest  and  safest  ways  of  disposing  of  excretions  in  the 
country  is  to  keep  them  dry  by  covering  them  with 
ashes  or  dry  earth.  If  this  is  done,  flies  will  not  crawl 
over  the  excretions,  and  there  will  be  no  drainage  from 
them  into  the  underground  water  from  which  wells 
are  supplied. 

Disposal  of  Slops  in  the  Country. — The  waste 
water  which  has  been  used  in  bathing,  laundering,  and 
house  cleaning  often  contains  disease  germs.  When  the 
slops  are  thrown  upon  the  ground,  they  sink  into  the 
soil.  The  upper  layer  of  the  soil  always  contains 
bacteria  which  oxidizes  and  destroys  the  disease  germs 
and  other  impurities.  The  soil  also  screens  out  the 
solid  particles  from  the  sewage,  and  allows  only  pure 


EXCRETION  177 

water  to  soak  into  the  deeper  parts  of  the  soil.  Under- 
ground water  is  nearly  always  pure,  unless  a  great  deal 
of  dirty  water  is  poured  upon  the  ground  in  one  spot. 

Many  persons  allow  their  slops  to  flow  from  their 
kitchen  waste  pipes  upon  one  spot  until  the  ground  is 
soaking  wet,  and  the  useful  bacteria  of  the  soil  are 
drowned  from  want  of  air.  The  slops  and  waste 
matters  may  then  form  a  dirty  pool  from  which  disease 
germs  may  be  carried  away  by  flies  and  other  vermin. 
If  you  have  no  other  means  for  getting  rid  of  slops, 
catch  them  in  a  pail,  and  when  it  is  full,  empty  them  in 
the  back  yard  away  from  the  well,  first  on  one  spot 
and  then  on  another. 

Sewage. — The  waste  water  of  a  house  or  barn  is 
called  sewage.  Nearly  all  sewage  contains  excretions 
from  human  beings.  Sewage  will  contain  disease 
germs  when  it  contains  excretions  from  a  person  who 
has  an  infectious  disease.  It  often  spreads  diseases 
in  two  ways :  first,  by  flowing  into  drinking  water ; 
and  second,  by  being  carried  to  food,  or  to  the  mouth 
and  nose,  by  flies  or  by  other  means.  The  safe  dis- 
posal of  sewage  is  one  of  the  most  important  matters 
with  which  the  people  of  cities  and  towns  have  to  deal. 

Cesspools.  —  In  houses  with  bathrooms,  the  sewage 
contains  both  excretions  and  slops.  This  mixture 
may  not  be  emptied  on  the  ground  with  safety.  One 
way  to  dispose  of  it  is  to  empty  it  into  an  underground 
tank,  called  a  cesspool.  There  its  solid  parts  slowly 
decay  and  become  harmless,  and  the  liquid  soaks  into 

GEN.    HYG. 12 


178  EXCRETION 

the  soil.  A  cesspool  which  is  properly  constructed 
and  which  acts  properly  will  destroy  the  disease 
germs  which  may  be  in  the  sewage. 

If  a  cesspool  receives  more  sewage  than  the  soil  is 
able  to  purify,  the  sewage  will  reach  the  underground 
water  and  make  it  unfit  for  use.  The  underground 
water  in  villages  is  seldom  pure  if  cesspools  are  used. 

Sewage  from  a  cesspool  may  flow  along  an  under- 
ground rock  or  a  layer  of  water-tight  clay,  and  reach  a 
well  or  pump  from  which  drinking  water  is  taken. 
If  a  cesspool  and  a  well  must  both  be  placed  in  the 
same  yard,  locate  the  well  in  a  place  from  which 
both  the  ground  and  the  underground  rock  slope  away 
from  it. 

Another  danger  from  a  cesspool  is  that  flies  may 
carry  disease  germs  away  from  it,  or  mosquitoes  may 
breed  in  it.  A  cesspool  is  not  safe  unless  it  is  covered 
so  closely  that  flies  and  mosquitoes  cannot  enter  it. 

Sewers.  —  Cities  and  large  villages  make  more 
sewage  than  cesspools  can  safely  receive.  In  these 
places  the  sewage  is  taken  away  by  means  of  under- 
ground pipes,  called  sewers,  which  are  built  at  public 
expense.  The  sewage  from  a  small  city  would  make  a 
good-sized  stream,  and  that  from  a  large  city,  like 
New  York,  would  make  a  river.  It  is  difficult  to  get 
rid  of  this  great  quantity  of  sewage.  Many  cities, 
such  as  New  York,  Albany,  and  Troy,  empty  their 
sewage  into  the  nearest  body  of  water.  But  the  sewage 
makes  the  water  impure,  and  spoils  it  for  the  people  of 


EXCRETION  179 

other  cities  who  wish  to  use  the  river  water  for  drink- 
ing or  washing.  The  people  of  the  city  of  Albany 
take  their  drinking  water  from  the  Hudson  River,  and 
have  been  put  to  great  expense  in  removing  the  sewage 
which  is  poured  into  the  river  by  the  people  of  the  city 
of  Troy. 

Sewage  Disposal  Plant.  —  One  of  the  most  necessary 
public  works  for  a  city  or  large  village  is  a  sewage  dis- 


Filter  beds  in  a  sewage  disposal  plant. 

posal  plant  which  purifies  the'  sewage.  A  sewage  dis- 
posal plant  which  acts  properly  will  destroy  all  disease 
germs  which  may  be  in  the  sewage. 

One  of  the  best  forms  of  sewage  disposal  is  to  collect 
all  the  sewage  into  a  large  water-tight  cesspool,  called 
a  septic  tank,  where  its  solid  parts  decay  and  become 


i8o  EXCRETION 

liquefied  as  in  a  small  cesspool.  The  liquid  which 
overflows  from  the  tank  is  emptied  on  plots  of  sand, 
first  on  one,  and  then  on  another,  so  that  each  plot 
is  used  only  once  a  day.  The  soil  destroys  the  impuri- 
ties in  the  sewage,  just  as  the  soil  does  when  a  basin  of 
slops  is  thrown  on  the  ground  in  a  back  yard.  This 
method  of  getting  rid  of  sewage  is  almost  like  nature's 
own  way  of  purifying  dirty  water.  A  sewage  disposal 


Sewage  flowing  over  broken  stone. 

plant  that  is  run  properly  is  no  more  unpleasant  to 
sight  or  smell  than  a  stable  or  barn  yard. 

In  some  sewage  disposal  plants  the  impure  water 
which  flows  from  a  septic  tank  is  sprayed  upon  large 
beds  of  broken  stone  before  it  flows  upon  the  soil.  The 
stone  bed  removes  the  ^greater  part  of  the  impurities 
and  only  a  small  area  of  soil  is  needed  to  complete  the 
purification. 

Gas  Trap.  -  -  The  pipes  which  carry  waste  water 
away  from  houses  are  laid  sloping  so  that  the  water 
will  quickly  run  out  of  them.  The  waste  pipes  are 


EXCRETION 


181 


nearly  always  empty,  and  are  likely  to  let  foul-smelling 
gases  into  the  room,  unless  they  have  arrangements, 
called  traps,  to 
keep  the  gases  out. 

In  a  common 
form  of  trap,  the 
upright  part  of  the 
waste  pipe  under  a 
tub  or  basin  is  bent 
in  the  form  of  a 
deep  loop.  When 
the  tub  or  basin  is 
emptied,  the  loop 
of  the  pipe  remains 
full  of  water,  and 
prevents  gases 
from  escaping. 
The  plumbing  of  a  house  will  be  unsafe  unless  there 
is  a  trap  in  each  waste  pipe  under  the  sinks,  bathtubs, 
and  basins. 

Garbage.  —  The  solid  waste  matter  from  a  kitchen 
is  called  garbage.  It  consists  of  such  things  as  scraps 
of  food,  potato  peelings,  meat  rinds,  bones,  dirty  tin 
cans,  and  ashes.  These  are  often  thrown  in  a  pile 
behind  an  outbuilding.  Slops  are  often  thrown  over 
them,  making  a  foul  mass  in  which  disease  germs  live. 
House  flies  often  flit  back  and  forth  between  the  pile 
and  the  kitchen,  and  carry  filth  and  disease  germs 
to  food.  A  garbage  heap  is  dangerous  to  health. 


A  gas  trap  under  a  sink. 


182 


EXCRETION 


You  can  easily  get  rid  of  garbage  without  throwing 
it  into  heaps.     Feed  scraps  of  food  to  chickens  or  pigs, 

or  burn  them. 
Burn  or  bury 
everything  else 
that  will  decay. 

In  many  cities, 
the  garbage  is  col- 
lected at  public  ex- 


pense. 


and  sorted. 


Much  of  it  is  put 
to  use  so  as  to 
help  pay  the  cost 
of  its  disposal. 
For  example, 
grease  and  fat  are 

preserved  for  soap  making,  and  wood  and  paper  are 

burned  under  steam  boilers. 


A  garbage  heap  is  a  breeding  place  of  diseases. 


QUESTIONS 

What  is  an  excretion? 

Name  the  principal  excretions  of  the  body. 
What  are  the  principal  organs  of  excretions  ? 
What  substances  are  excreted  by  the  lungs  ? 
What  substances  are  excreted  by  the  kidneys  ? 
What  substances  does  the  skin  excrete  ? 
What  substances  are  excreted  by  the  intestine  ? 
How  does  drinking  plenty  of  water  help  the  kidneys  and 
skin  to  excrete  waste  matters  ? 

How  much  water  does  a  person  need  to  drink  each  day  ? 


EXCRETION 


183 


What  effect  does  alcohol  have  on  the  excretions  of  the  body  ? 

How  do  the  excretions  of  the  body  help  to  spread  diseases  ? 

What  is  sewage? 

How  does  the  soil  destroy  disease  germs  when  sewage  is 
thrown  upon  it  ? 

Describe  a  good  way  to  get  rid  of  the  waste  water  from  a 
kitchen  sink. 

What  is  a  cesspool? 

What  becomes  of  the  excretions  which  are  run  into  a  cess- 
pool? 

What  are  the  dangers  from  a  cesspool  ? 

What  is  a  sewer? 

Describe  a  sewage  disposal  plant. 

What  is  a  septic  tank  ? 

What  is  a  gas  trap? 

What  are  some  of  the  dangers  which  arise  from  a  garbage 
heap? 

How  can  you  dispose  of  garbage  safely  ? 


CHAPTER   XVIII 
WATER   SUPPLY 

Quantity  of  Water  Needed  Daily.  —  Each  grown 
person  needs  about  three  quarts  of  water  to  replace 
that  which  passes  off  from  the  body  each  day.  One 
or  two  gallons  of  water  will  be  needed  for  preparing 
and  cooking  his  food,  and  for  washing  dishes ;  and  at 
least  another  gallon  will  be  required  in  washing  and 
bathing  the  body.  Each  person  requires  at  least  three 
gallons,  or  one  large  pailful,  of  water  each  day. 

In  many  families  each  person  uses  at  least  five 
gallons  a  day  in  bathing,  laundering,  and  house  clean- 
ing. If  the  house  has  a  bathroom,  this  quantity  will 
be  much  more  than  doubled.  A  great  deal  of  water  is 
also  used  in  stables  and  in  the  care  of  animals.  A  city 
has  to  supply  at  least  thirty  gallons  a  day  for  each 
person.  London  supplies  thirty-five  gallons  a  day  for 
each  inhabitant.  New  York  supplies  one  hundred 
and  thirty  gallons,  but  much  of  it  is  wasted. 

Source  of  Water  Supplies.  -  -  The  simplest  way  to 
get  a  supply  of  water  is  to  take  it  from  a  natural  spring, 
or  stream,  or  lake.  Another  way  is  to  dig  a  well,  or 
drive  a  pump,  so  as  to  reach  the  underground  water. 
Another  way  is  to  catch  rain  water  from  a  roof  and 

store  it  in  a  cistern. 

184 


WATER   SUPPLY 


185 


Those  who  live  in  cities  and  large  towns  draw  water 
from  pipes  which  connect  with  the  public  waterworks, 
but  the  water  usually  comes  from  streams  or  lakes. 

There  are  differences  in  the  taste  and  appearance  of 
water  from  various  places.  The  differences  are  due  to 
substances  which  are  contained  in  the  water. 

What  is  in  Water.  —  Water  always  has  substances 
dissolved  in  it.  The  purest  water  is  rain  water,  but 
that  has  air  in  it.  If  we  could  get  water  with  nothing 
dissolved  in  it,  we  would  not  like  it,  for  the  pleasant 
taste  of  good,  water  comes  from  the  air  which  is  dis- 
solved in  it. 

Boil  some  water  in  a  clean  kettle  for  five  minutes. 
It  will  now  taste  flat  and  unpleasant,  for  most  of  its 
air  has  passed  off  with  the  steam.  Now  stir  or  shake 
it  to  a  foam  so  that  it  will  become  mixed  with  air. 
It  will  now  taste  like  fresh  water  again. 

Underground  water,  and  the  water  in  springs,  streams, 
and  lakes,  comes  from  rain  or  snow.  As  the  water 
soaks  through  the  ground,  it  dissolves  lime,  salt,  and 
other  minerals  from  the  soil.  Nearly  all  underground 
water  has  a  little  lime  and  salt  dissolved  in  it. 

Let  a  drop  of  clear  water  dry  on  a  clean  glass.  It 
will  leave  a  whitish  spot  of  minerals  which  had  been 
dissolved  in  the  water.  You  can  often  see  these  spots 
of  minerals  on  a  window  after  it  has  been  washed. 

Soft  and  Hard  Water. — The  minerals  in  water  are 
often  too  small  in  quantity  to  be  noticed.  Such  water 
is  called  soft  water. 


i86  WATER   SUPPLY 

In  some  places  the  water  has  so  much  lime  dissolved 
in  it  that  the  minerals  form  a  scum  when  soap  is  added 
to  the  water.  Such  water  is  called  hard  water.  The 
minerals  in  hard  water  do  not  make  it  unfit  for  drink- 
ing. Hard  water  is  sometimes  not  good  for  cooking, 
for  some  foods,  such  as  peas  and  beans,  do  not  easily 
become  soft  when  they  are  boiled  in  it. 

Mineral  Water.  —  If  water  has  a  great  deal  of  min- 
eral substances  dissolved  in  it,  we  call  .it  a  mineral 
water.  Some  mineral  waters  are  bubbling  full  of  car- 
bon dioxide  which  gives  them  a  pleasant  taste  and  a 
sparkling  appearance.  Some  waters  contain  sulphur, 
or  iron,  or  potash,  or  other  minerals  which  are  used  as 
medicines.  The  good  effects  of  drinking  mineral 
water  come  from  the  water  itself  as  much  as  from  the 
minerals  which  are  dissolved  in  it,  for  many  persons 
who  usually  drink  too  little  water  will  drink  large 
quantities  of  mineral  water. 

Impurities  in  Water.  —  Most  of  the  water  which  is 
used  in  houses  contains  either  pieces  of  wood  and 
leaves,  or  bits  of  iron  rust,  or  particles  of  clay  and  mud. 
A  little  of  them  will  do  no  harm,  but  if  the  water  is 
muddy,  or  colored,  or  tastes  bad,  it  will  be  likely  to 
harm  those  who  drink  it. 

Almost  the  only  dangerous  impurities  in  water  are 
disease  germs.  The  principal  reason  why  dirty  water 
is  harmful  is  because  disease  germs  are  often  found  in 
the  dirt.  But  disease  germs  may  be  in  water  which  is 
clear  and  sparkling,  and  is  pleasant  to  the  taste. 


WATER    SUPPLY  187 

How  Disease  Germs  get  into  Water.  —  Dirty  water 
will  not  produce  a  disease  unless  it  contains  living 
germs  of  the  disease.  Disease  germs  are  not  produced 
by  dead  leaves,  or  grass,  or  sticks,  or  mud.  They  are 
formed  only  in  the  bodies  of  sick  persons  or  animals. 
If  they  are  in  water,  it  is  because  they  came  there  with 
the  excretions  and  sewage  from  a  sick  person,  or  a  sick 
animal.  Keeping  water  pure  means  keeping  it  free 
from  sewage  and  from  dirty  water  from  houses  and 
barnyards.  Nearly  all  the  dangerous  impurities  in 
water  come  from  human  beings. 

Diseases  caused  by  Impure  Water.  —  The  principal 
kinds  of  disease  germs  which  are  found  in  impure  water 
are  those  which  cause  stomach  aches,  typhoid  fever, 
and  other  diseases  of  the  intestine.  Most  rivers  which 
flow  past  farms  or  towns  contain  sewage,  and  many  of 
the  people  who  drink  the  water  of  the  rivers  are  made 
sick,  unless  the  water  is  purified  before  it  is  used. 
Hundreds  of  people  die  each  year  in  the  United  States 
from  typhoid  fever  which  is  caught  from  drinking  water 
containing  sewage.  Nearly  all  of  these  deaths  are 
due  to  carelessness  and  neglect,  and  could  easily  be 
prevented  by  taking  proper  care  of  sewage.  In  one 
small  city  over  a  thousand  persons  caught  typhoid 
fever  because  the  slops  from  a  person  sick  with  typhoid 
fever  were  thrown  upon  a  frozen  hillside,  and  later 
were  washed  into  the  river  which  supplied  the  city  with 
drinking  water. 

Pure  Drinking  Water  in  the  Country.  —  People  in 


1 88  WATER   SUPPLY 

the  country  usually  get  their  drinking  water  from  wells 
which  are  sunk  into  the  underground  water.  This 
water  is  nearly  always  pure,  unless  some  ignorant  or 
careless  person  allows  excretions,  or  slops,  or  barn- 
yard drainage  to  run  'into  the  well,  or  into  the  under- 
ground water  which  feeds  it. 

Many  wells  are  unfit  for  use  because  they  are  placed 
over  underground  streams  of  dirty  water  flowing  from 


An  unsafe  well. 

cesspools,  or  wet  barnyards,  or  from  dumping  places 
for  slops  and  excretions.  The  place  for  a  well  is  on  the 
highest  part  of  a  yard,  so  that  all  dirty  water,  both 
from  the  surface  and  from  underground,  will  flow  away 
from  it. 

If  a  spring  or  well  is  open  at  the  top,  or  has  sides  of 


WATER    SUPPLY 


189 


brick  or  stone,  dirty  surface  water,  worms,  and  other 
impurities  may  fall  into  it,  or  may  drop  through  cracks 
in  the  bricks  or  stones.  An  old-fashioned  open  well 
is  not  safe,  even  if  the  underground  water  is  pure  when 
it  flows  into  the  well.  A  well  made  by  driving  a  small 
iron  pipe  into  the  ground  is 
safe  if  the  underground  water 
is  pure,  for  no  dirt  can  fall 
down  it. 

Pure  Drinking  Water  in 
Cities.  -  -  The  people  of  cities 
have  their  water  brought  to 
their  houses  through  aque- 
ducts and  pipes  which  are  fed 
from  public  waterworks.  If 
the  water  in  the  works  is 
pure,  the  water  in  the  houses 
will  also  be  pure,  for  nothing 
can  get  into  the  pipes  except 
that  which  conies  from  the 
waterworks. 

Many  cities  take  their  water  from  rivers  or  lakes 
which  contain  sewage.  If  they  do  not  purify  their 
water,  they  have  more  typhoid  fever  than  those  which 
do  purify  it,  or  which  take  their  water  from  pure 
sources.  In  the  city  of  Albany,  during  the  ten 
years  following  the  year  1900,  there  was  only  one 
fourth  as  much  typhoid  fever  as  there  was  during 
the  ten  years  before  1900,  because  since  1900  the 


A  driven  pump. 


i  go 


WATER   SUPPLY 


Aqueduct  which  brings  water  from  the  Cats- 
kill  Mountains  to  New  York. 

in  purifying  drinking  water,   but 
make  impure  water  entirely  safe. 


public  water  has 
been  purified  be- 
fore being  sent 
through  the  city. 
Reservoirs. - 
One  way  of  purify- 
ing drinking  water 
is  to  store  it  in  a 
reservoir  for  a  few 
days.  The  dirt 
and  mud,  and 
most  of  the  bac- 
teria, will  sink  to 
the  bottom,  and 
the  sunlight  will 
kill  many  of  the 
bacteria.  A  reser- 
voir is  a  great  help 
it  alone  will  not 


Water  filtration  plant  of  Albany,  N.  Y. 


WATER   SUPPLY 


191 


Interior  of  a  filter  tank  in  the  Albany  filtration  plant. 

Filtration.  —  One  of  the  easiest  and  best  ways  of 
purifying  water  is  to  pass  it  through  a  large  bed  of 
sand,  called  &  filter,  which  strains  out  dirt  and  bacteria. 
The  soil  is  a  great  filter  (p.  176).  If  a  filter  is  very 
large,  and  the  water 
passes  through  it 
slowly,  it  will  take 
out  very  nearly  all 
the  dirt  and  disease 
germs  that  may  be 
in  the  water.  Al- 
bany, Philadelphia, 
and  many  other 
large  cities  which 
have  to  take  their 

water  from    impure        Water  gates  in  the  Albany  filtration  plant. 


IQ2 


WATER    SUPPLY 


rivers,  pass  the  water  through  great  filters,  and  by 
doing  so  they  protect  thousands  of  persons  from  sick- 
ness, and  hundreds  from  death  each  year. 

If  a  filter  is  small,  or  if  water  is  run  rapidly  through 
it,  the  flow  of  water  will  wash  bacteria  and  disease 
germs  through  it  as  if  it  were  a  sieve.  For  this  reason 
the  small  filters  sold  for  use  in  kitchens  will  not  purify 
the  water. 

Purifying  Water  by  Boiling.  —  If  drinking  water  is 
not  pure,  we  can  make  it  safe  for  use  by  boiling  it, 
for  a  boiling  heat  will  kill  the  disease  germs.  Many 
persons  who  fear  to  drink  plain  water  drink  tea  or 
coffee.  The  tea  or  coffee  which  is  added  to  the  water 
does  not  make  the  water  safe,  but  the  heat  of  boiling 
the  drink  kills  the  disease  germs  in  the  water.  The 
Chinese  are  able  to  drink  dirty  river  water  with  safety, 
because  they  boil  the  water  which  they  drink,  and  cook 
all  their  food  before  eating  it. 

Water  which  has  been  boiled  for  some  minutes 
tastes  bad,  because  the  boiling  drives  the  air  from  it 
(p.  185).  If  the  water  is  taken  from  the  fire  as  soon 
as  it  begins  to  boil,  the  disease  germs  which  may  be 
in  it  will  be  killed,  but  the  water  will  not  lose  its  air, 
and  its  taste  will  not  be  changed. 

Ice.  —  Ice  taken  from  impure  water  will  contain 
disease  germs  if  the  water  contained  germs  before  it 
froze.  Those  who  work  or  skate  on  the  ice  may  leave 
disease  germs  on  it,  or  the  ice  may  be  soiled  by  the 
dirty  hands  or  dirty  clothes  of  those  who  handle  it. 


WATER    SUPPLY  193 

Cold  will  not  kill  the  germs,  but  they  will  grow  as  soon 
as  the  ice  melts.  The  purity  of  the  ice  which  is  put 
into  food  and  water  is  of  as  much  importance  as  the 
purity  of  the  food  and  the  water  themselves. 

Washing  with  Impure  Water.  —  Impure  water  which 
is  used  in  bathing  the  body  or  in  washing  dishes  may 
be  the  cause  of  spreading  diseases.  Milk  cans  which 
have  been  washed  in  impure  water  have  often  been  the 
cause  of  typhoid  fever  in  those  who  have  taken  milk 
from  the  cans.  It  is  almost  as  dangerous  to  use  im- 
pure water  for  washing  as  for  drinking. 

Examining  Water.  —  We  cannot  always  tell  whether 
or  not  water  is  fit  to  drink  by  looking  at  it,  or  smelling 
it,  or  tasting  it,  but  we  may  be  sure  that  water  is  not 
fit  for  use  if  it  is  colored,  or  cloudy,  or  has  an  unpleasant 
taste  or  smell. 

We  can  tell  a  great  deal  about  the  purity  of  water 
by  examining  the  country  around  the  well  or  stream 
from  which  it  comes.  If  any  drainage  from  houses, 
or  barnyards,  or  cesspools  is  found  near  it,  the  water 
is  likely  to  be  unsafe  for  drinking. 

Water  which  looks,  smells,  and  tastes  good  may  still 
contain  disease  germs.  If  the  germs  are  present, 
they  may  be  found  by  a  trained  chemist  or  doctor. 
The  boards  of  health  of  many  of  the  states  and  large 
cities  will  examine  public  water  supplies  free  of  charge. 

Public  Drinking  Cups.  —  Drinking  cups  are  often 
placed  in  schools,  in  railroad  trains  and  stations,  and 
in  public  buildings,  to  be  used  by  any  one  who  wants  a 

GEN.   HYG. 13 


194 


WATER   SUPPLY 


drink.     Every  person  who  takes  the  cup  between  his 
lips  leaves  mucus,   and  epithelial  cells,   and  bacteria 

from  the  mouth 
upon  the  rim  of 
the  cup,  and  the 
next  person  who 
drinks  from  the 
cup  takes  some  of 
them  into  his 
mouth,  and  leaves 
more  from  his  own 

Paper  drinking  cups.  mouth      Upon       the 

cup.     Some  one  who  has  a  cold,  or  a  sore  throat,  or 

a  worse  disease,  is  almost  sure  to  use  the  cup  and  to 

leave     disease     germs 

upon  it.    Tuberculosis 

and  diphtheria  are  two 

diseases  which    are 

likely  to  be  spread  by 

the   use   of   the  cups. 

Public   drinking   cups 

are  so  dangerous  that 

some  states  have  laws  -^    j^n— 

that    none    shall     be 

placed   in   any  public 

place  in  those  states. 

Paper  drinking  cups  A  safe  drinkins  fountain' 

are  often  placed  in  public  drinking  fountains,  and  are 
for  sale  at  drug  stores  and  stationers.     They  are  to  be 


WATER   SUPPLY  195 

thrown  away  as  soon  as  they  have  been  used.  They 
are  cheap  and  may  easily  be  carried.  Take  some  with 
you  and  use  them  when  you  go  away  from  home,  or 
when  you  start  on  a  journey. 

A  safe  form  of  public  drinking  place  is  one  in  which 
the  water  bubbles  up  in  a  stream  about  as  large  as  your 
finger,  and  about  an  inch  high.  You  drink  by  placing 
your  lips  to  the  running  stream.  In  drinking  in  this 
way  you  run  no  danger  of  taking  anything  which 
another  person  has  left  at  the  fountain. 

If  you  must  use  a  public  drinking  cup,  do  not  take 
the  rim  between  your  lips,  but  touch  both  lips  to  the 
water  inside  the  rim.  In  this  way  your  lips  will  touch 
nothing  except  the  water  of  the  cup. 


QUESTIONS 

How  much  water  does  a  man  need  to  take  into  his  body  each 
day? 

About  how  much  water  will  each  person  in  a  family  use  in  a 
day? 

What  substances  are  always  found  in  water  ? 

Of  what  use  is  air  in  water  ? 

What  is  meant  by  hard  water  ? 

What  are  mineral  waters  ? 

Of  what  do  the  common  impurities  in  water  consist  ? 

What  are  the  most  dangerous  impurities  in  water  ? 

How  do  disease  germs  get  into  water  ? 

WTiat  diseases  are  often  caused  by  impure  water  ? 

WTiy  is  water  from  an  open  well  not  so  safe  as  water  taken 
from  a  driven  pump  ? 


ip6  WATER   SUPPLY 

How  does  storing  water  in  a  reservoir  help  to  purify  it  ? 

What  is  a  filter? 

How  does  boiling  purify  impure  water  ? 

How  may  ice  be  a  means  of  spreading  diseases  ? 

How  can  you  tell  whether  or  not  a  water  supply  is  pure  ? 

What  harm  is  often  done  by  the  use  of  public  drinking  cups  ? 

Describe  a  safe  form  of  drinking  fountain  for  schools. 

How  can  you  drink  from  a  public  cup  with  the  least  danger  ? 


CHAPTER  XIX 

VERMIN 

How  Insects  cause  Diseases.  —  Men  used  to  think 
that  flies,  mosquitoes,  and  other  insects  did  not  harm  a 
person's  health,  except  by  causing  a  tickling  and  itch- 
ing when  they  bit  the  skin.  It  is  now  known  that 
many  of  them  are  disease  carriers,  and  are  dangerous 
to  health  and  life.  Nearly  all  insects  that  bite  the 
body  may  carry  diseases  from  a  sick  person  or  animal 
to  the  next  person  or  animal  whom  they  bite.  The 
most  common  and  most  dangerous  insects  that  affect 
the  health  are  flies,  mosquitoes,  cockroaches,  lice,  bed- 
bugs, and  fleas. 

Cats  and  dogs  may  also  carry  diseases  to  man. 
Insects  and  other  small  animals  which  are  troublesome 
to  man,  or  are  harmful  to  health,  are  called  vermin. 

Bee  Stings. — The  stings  of  bees  and  wasps  cause 
swellings  which  are  painful  for  a  short  time,  but  they 
are  not  the  cause  of  any  disease,  for  none  of  the  in- 
sects go  from  person  to  person  as  flies  and  mosquitoes 
do.  Most  insects  which  are  harmful  bite  in  order  to 
get  food,  but  bees  and  wasps  sting  only  to  protect 
themselves  from  harrn.^  If  one  buzzes  around  your 
head,  it  will  not  touch  you  if  you  keep  still  and  do 
not  annoy  it. 

197 


i98 


VERMIN 


A  bee  stings  by  means  of  a  hollow  spear  which  it 
thrusts  into  the  skin  from  the  hinder  part  of  its  body. 
The  spear  itself  is  too  small  to  hurt,  but  the  bee  uses 
it  to  force  a  bit  of  poison  into  the  skin.  This  poison 
is  what  causes  the  swelling  and  the  pain  of  the  sting. 
You  can  relieve  the  pain  somewhat  by  pinching  the 
skin  so  as  to  squeeze  the  poison  out  of  the  flesh.  Cold 
water,  or  a  little  ammonia  rubbed  on  the  spot  will 
also  help  to  relieve  the  pain. 

Danger  from  House  Flies.  —  A  house  fly  cannot 
bite,  or  sting,  or  scratch,  and  yet  it  is  dangerous 

because  of  the 
places  which  it 
visits  in  search  t>f 
food.  It  lights 
upon  garbage 
heaps  and  excre- 
tions, and  in  dirty 
stables,  where  its 
legs  and  body  be- 
come soiled  with 
filth  and  disease 
germs.  It  then 
flits  into  houses 
and  crawls  upon  food  and  over  the  mouths  and  eyes 
of  helpless  babies,  dropping  disease  germs  wherever  it 
goes.  The  blue  flies,  which  may  often  be  seen  swarm- 
ing over  decaying  meat,  may  also  be  the  carriers  of 
disease  germs. 


House  flies  and  bluebottle  flies. 


VERMIN 


199 


A  fly's  body  and  legs  are  covered  with  stiff  hairs, 
which  catch  dirt  and  filth.  Under  a  microscope  the 
fly  looks  like  a  bristly  pig  that  has  been  wallowing  in 
the  dirt.  It  tries  to  keep  itself  clean,  for  it  often  rubs 
its  feet  together,  and  brushes .  its  front  legs  over  its 
head,  as  a  cat  does.  It  is  usually  covered  with  bacteria 
which  it  gets  from  the  dirty  places  where  it  alights. 
Shaking  a  fly  in  a 
bottle  of  water  will 
often  wash  more 
then  a  million  bac- 
teria from  its  body. 
A  fly  which  falls 
into  a  milk  pitcher 
usually  leaves 
thousands  of  bac- 
teria and  disease 
germs  in  the  milk. 

The  most  com- 
mon forms  of  sick- 
ness  that  are 
spread  by  house  flies  are  typhoid  fever  and  other 
intestinal  diseases.  Many  of  the  stomach  diseases 
of  babies  are  caused  by  disease  germs  which  flies 
have  left  in  the  children's  milk  or  in  their  mouths. 
Sore  eyes  are  often  caused  by  flies  crawling  over  a 
baby's  face.  Consumption  is  often  spread  by  flies. 

Protection   against   Flies.  —  A   house   fly   will   not 
carry  disease  germs  if  it  cannot  go  where  it  can  pick 


House  fly.     Magnified. 


20O 


VERMIN 


them  up.  Keep  flies  out  of  all  sick  rooms.  Cover  all 
excretions  and  sewage  fly-tight.  Clean  up  the  gar- 
bage heaps  in  the  back 
yard,  and  either  burn  or 
bury  all  decaying  matter. 
If  everybody  did  these 
things,  flies  would  not 
carry  diseases,  for  they 
could  not  get  the  germs 
on  their  bodies. 

Another  method  of  pro- 
tection against  flies  is  to 
cover  windows  and  doors 
with  screens  and  fly  netting 
in  order  to  keep  all  flies 
out  of  the  house  and  away 
from  food.  A  swarm  of  flies  in  a  kitchen  or  dining 
room  is  far  more  dangerous  than  a  swarm  of  bees.  In 
the  Spanish  war  the  number  of  soldiers  who  were  killed 
by  house  flies  was  five  times  the  number  of  those 
killed  by  bullets,  for  the  flies  spread  typhoid  fever 
through  the  camps. 

The  Life  of  a  Fly.  —  A  fly  lives  only  half  of  its  life 
as  a  winged  creature.  During  the  first  half  of  its  life 
it  looks  like  a  worm,  and  is  called  a  maggot.  Every 
maggot  in  a  manure  pile,  or  garbage  heap,  or  mass  of 
decaying  filth,  is  a  young  fly. 

Maggots  hatch  from  eggs  which  are  laid  by  winged 
flies  in  stable  cleanings,  wet  garbage,  decaying  meat, 


Maggots  on  a  heap  of  fertilizer. 


VERMIN  201 


and  wet  filth  of  all  kinds.  The  maggots  reach  their 
growth  in  about  a  week.  Their  skins  then  harden  into 
brown  shells,  called  pupa  cases,  which  look  like  fat 
grains  of  wheat.  The  young  flies  lie  quietly  in  the 


Life  history  of  a  house  fly. 

cases  for  a  few  days  and  then  come  out  as  full-grown 
flies  with  wings. 

Getting  rid  of  Flies.  —  If  there  were  no  manure 
piles,  or  garbage  heaps,  or  other  masses  of  decaying 
filth,  there  would  be  no  places  in  which  flies  could 
hatch  or  grow,  and  soon  there  would  be  no  flies  left 
alive.  Remove  all  manure  piles  and  garbage  heaps  at 
least  once  every  week.  Keep  all  stables  and  barnyards 
clean  and  dry.  Doing  these  things  throughout  a  town 
will  rid  the  place  of  flies. 

The  time  to  begin  to  fight  flies  is  early  in  the  spring. 
Only  a  few  flies  live  through  the  winter,  and  all  that 
are  seen  in  the  following  summer  are  descended  from 
them.  Each  fly  lays  over  a  hundred  eggs,  and  the  new 


202 


VERMIN 


brood  is  ready  to  lay  eggs  within  two  or  three  weeks. 
Every  maggot  or  fly  that  is  killed  in  the  spring  and  early 
summer  means  thousands  less  flies  later  in  the  season. 

Cattle  Flies.  —  Many  of  the  flies  which  bite  horses 
and  cattle  look  almost  like  house  flies.  They  often 
come  into  houses  and  bite  persons,  and  are  sometimes 
the  carriers  of  diseases.  The  disease  called  the  spinal 
paralysis  of  children  may  be  spread  by  the  bite  of  stable 
flies  which  have  bitten  another  person  that  has  the 
disease.  Stable  flies  often  spread  diseases  among  horses 
and  cattle  in  Africa.  Stable  flies  are  born  and  bred  in 
decaying  filth  and  dirty  barnyards,  just  as  house  flies 
are.  We  may  get  rid  of  them  by  doing  the  same 
things  that  prevent  house  flies  from  rearing  their  young. 

Mosquitoes 
and  Diseases.  - 
Certain  kinds  of 
mosquitoes  are 
the  means  of 
spreading  mala- 
ria and  yellow 
fever,  and  for 
this  reason  they 
have  been  the 
cause  of  some  of 
the  worst  epi- 


V 
J  j. 


v1#W&#! 


Mosquito  eggs  and  wigglers. 

world  has  ever  seen.     The  discovery  that  mosquitoes 
will  carry  diseases  was  made  about.  the  year   1900. 


VERMIN  203 

Before  that  time  a  great  difficulty  in  living  in  Panama 
and  Havana  was  to  avoid  catching  malaria  and  yellow 
fever.  These  diseases  have  almost  disappeared  from 
those  places  since  the  time  that  the  United  States 
government  has  required  the  inhabitants  to  destroy  all 
mosquitoes. 

Malaria  is  caused  by  living  germs  which  grow  in  the 
blood.  A  mosquito  that  sucks  blood  from  some  one 
who  has  malaria  takes  the  germs  into  its  body,  and 
afterward  gives  them  to  persons  whom  it  bites.  The 
germs  of  malaria  will  live  in  only  a  few  kinds  of  mos- 
quitoes, but  these  kinds  are  scattered  over  a  large  part 
of  the  earth,  and  may  grow  wherever  other  kinds  grow. 

One  way  of  telling  a  malarial  mosquito  is  by  its  posi- 
tion when  it  alights,  for  it  seems  to  stand  on  its  head 
with  the  hinder  part  of  its  body  pointing  away  from  the 
surface  on  which  it  stands.  It  has  spots  on  its  wings. 

Yellow  fever  is  caught  in  the  same  way  that  malaria 
is  caught,  but  the  mosquito  which  carries  the  germs  of 
yellow  fever  usually  grows  only  in  warm  countries, 
for  freezing  kills  it. 

Life  History  of  a  Mosquito.  —  Mosquitoes  hatch 
from  eggs  which  are  laid  by  the  full-grown  insects  in 
any  bit  of  quiet  water  that  they  can  find.  The  eggs 
are  black,  and  look  like  flakes  of  soot  floating  on  the 
water. 

Young  mosquitoes  are  the  tiny  creatures,  called 
wigglers,  that  may  often  be  seen  in  rain  barrels  resting 
at  the  surface  of  the  water,  and  wiggling  themselves 


204 


VERMIN 


Mosquito  eggs,  wigglers,  and  full-grown  mos- 
quito.    Magnified. 


away  when  they 
are  disturbed. 
They  are  found  in 
all  kinds  of  stag- 
nant water,  such 
as  marshes  and 
mud  puddles,  and 
pails  and  cans  of 
dirty  water.  Cess- 
pools are  often  full 
of  them,  and  even 
vases  of  flowers 
may  contain  them. 
About  two  weeks 

after  they  hatch,  the  wigglers  change  to  winged  mos- 
quitoes which   fly   away,  leaving   their  empty  skins 

floating  on  the  water. 

How  to  get  rid  of  Mosquitoes.  —  We  can  get  rid  of 

mosquitoes  by  destroying  them  in  their  breeding  places. 

If    mosquitoes    can 

find     no     stagnant 

water   in  which  to 

lay   their   eggs,   no 

young    ones    can 

grow.     Very    many 

of    the    mosquitoes 

around   houses    are 

hatched  in  pails,  tin 

Cans,   and   rain   bar-  A  small  ditch  where  mosquitoes  breed. 


VERMIN 


205 


rels.  If  these  vessels  of  water  are  emptied  once  a 
week,  young  mosquitoes  will  not  have  time  to  become 
full  grown  in  them. 

Wigglers  must  come  to  the  surface  of  the  water  to 
breathe.  If  kerosene  or  other  oil  is  poured  on  the 
water,  the  wigglers  cannot  get  air,  and  they  soon 
drown.  A  teaspoonful  of  kerosene  poured  into  a  barrel 


Wigglers  in  the  ditch. 

of  rain  water  will  kill  all  the  wigglers  in  it,  and  will  not 
harm  the  water  for  washing  purposes. 

The  principal  breeding  places  for  mosquitoes  are 
swamps  and  marshes  that  are  full  of  stagnant  pools. 
We  may  dry  up  the  pools  by  digging  ditches  which 
will  drain  off  the  water  and  leave  the  surface  dry.  No 
mosquitoes  can  then  grow  except  in  the  ditches,  and 
there  they  will  be  eaten  by  fish,  or  carried  away  by  the 
current  of  water.  Many  of  the  marshes  near  New 
York  city  have  been  freed  from  mosquitoes  by  being 
drained. 


206  VERMIN 

Cockroaches.  —  Cockroaches  are  long,  brownish  in- 
sects that  live  in  cracks  of  kitchen  floors,  and  among 
the  water  pipes,  and  in  dark,  damp  places  in  houses. 
They  do  not  bite  persons,  but  they  live  upon  garbage 
and  filth,  and  may  be  the  means  of  carrying  disease 
germs  to  food  as  they  crawl  over  it.  They  may  be 
killed  by  means  of  insect  powder.  If  floors  of 
kitchens  and  bathrooms  are  tight,  and  the  plumbing  of 
the  house  is  open  and  clean,  the  insects  cannot  find 
hiding  places,  but  may  be  easily  killed. 

Lice.  —  A  few  kinds  of  insects  may  make  their  home 
on  a  person's  body,  and  live  by  sucking  his  blood. 
The  most  common  kind  of  insect  on  the  body  is  a  louse 
that  lives  among  the  hairs  of  the  head.  These  lice 
are  spread  from  one  person  to  another  by  means  of  hats 
and  clothes.  They  cause  a  tickling  and  itching  by 
their  crawling  and  biting,  and  may  cause  a  person 
great  annoyance.  Sometimes  a  person  may  make  his 
skin  sore  by  scratching  the  itching  spot. 

Lice  hatch  from  white  eggs  which  are  about  the 
size  of  grains  of  sand.  They  are  called  nits,  and  are 
fastened  to  the  hairs  close  to  the  skin.  If  the  eggs  are 
found  at  a  distance  from  the  skin,  they  have  been  laid 
for  so  long  a  time  that  the  growth  of  the  hair  has 
carried  them  away  from  the  skin. 

Washing  the  hair  in  strong  soap  suds,  to  every  pint 
of  which  a  tablespoonful  of  kerosene  has  been  added, 
will  kill  the  lice,  but  the  eggs  may  remain  alive  and 
hatch  a  new  brood.  After  using  the  kerosene,  soak 


VERMIN  207 

the  hair  in  weak  vinegar  in  order  to  dissolve  the  glue 
which  binds  the  eggs  to  the  hair.  The  eggs  may  then  be 
washed  away,  and  the  head  entirely  freed  from  the  lice. 

Another  kind  of  louse 
lives  on  the  trunk  of  the 
body.  These  lice  lay  their 
eggs  on  the  underclothes. 
Cleanliness  and  boiling  the 
clothes  will  rid  the  body  of 
the  lice. 

Bedbugs.  —  Bedbugs  are 

,  n    ,      •  i  Body  lice  and  eggs.    Magnified. 

brown,    flat    insects    about 

an  eighth  of  an  inch  in  length.  They  live  by  sucking 
a  person's  blood,  and  may  carry  a  disease  from  one 
person  to  another.  One  disease  which  they  may  carry 
is  typhus  fever.  In  the  daytime  bedbugs  usually 
crawl  into  cracks  in  bedsteads,  walls,  and  floors.  They 
can  live  for  months  without  food.  They  have  no  wings 
and  can  crawl  but  slowly,  and  will  not  be  found  in  a 
house  unless  some  one  brings  them  there.  We  may 
keep  ourselves  and  our  houses  clear  of  them  by  keep- 
ing our  clothes  and  rooms  clean. 

Fleas.  —  Fleas  are  small,  brown  insects  that  move 
by  long  jumps.  They  are  often  found  on  dogs,  cats, 
rats,  and  other  lower  animals.  They  sometimes  jump 
upon  the  bodies  of  persons.  They  live  by  sucking 
blood,  and  may  carry  disease  germs  from  fcne  person 
or  animal  to  another. 

The  plague  is  a  disease  of  rats  as  well  as  of  mankind. 


208  VERMIN 

It  is  usually  spread  by  means  of  the  bites  of  fleas  which 
have  taken  the  germs  from  diseased  rats.  This  disease 
killed  millions  of  people  in  Europe  a  few  hundred  years 
ago,  and  is  still  found  in  uncivilized  parts  of  the  world. 
The  two  principal  means  of  preventing  the  spread  of 
the  disease  in  a  town  is  by  killing  all  the  rats  in  the 
place,  and  by  keeping  dwelling  houses  so  clean  that 
fleas  will  not  live  in  them. 

Rats  and  Mice.  —  Rats  may  become  sick  with  several 
diseases  which  persons  may  take  from  them.  Besides 
the  plague,  they  may  also  have  leprosy  and  tapeworm, 
and  may  spread  the  diseases  to  man.  Both  rats  and 
mice  may  also  carry  disease  germs  in  dirt  on  their 
bodies,  and  may  spread  them  to  food  and  drinking 
water. 

The  best  way  to  get  rid  of  rats  and  mice  is  to  remove 
garbage  heaps  and  loose  grain  on  which  they  feed,  and 
to  clean  up  dirty  cellars  and  piles  of  old  boards  and  hay 
in  which  they  hide  out  of  the  way  of  danger. 

Stray  Cats  and  Dogs.  — When  we  say  that  a  dog  or 
cat  is  mad,  we  mean  that  'it  has  the  disease  called 
rabies,  or  hydrophobia.  Rabies  is  caused  by  germs  which 
grow  in  the  brains,  and  are  also  found  in  the  mouths 
of  the  sick  animals.  Most  of  the  animals  and  persons 
that  have  rabies  catch  it  from  the  bites  of  homeless 
dogs  and  cats  on  the  streets.  A  public  dog-catcher, 
to  catch  all  stray  dogs  and  cats,  is  an  important  and 
useful  officer. 

The  bite  of  a  dog  or  cat  is  no  more  dangerous  than 


VERMIN  209 

the  prick  of  a  splinter  of  wood,  unless  the  animal  has 
rabies.  If  a  person  is  bitten  by  a  dog  or  cat,  do  not  kill 
the  animal,  but  shut  it  up  to  see  if  it  has  rabies.  If  it 
has  the  disease,  it  will  die  within  a  few  days.  If  it 
lives,  it  has  never  had  rabies,  and  there  is  no  danger 
that  its  bite  will  give  any  one  rabies. 

A  person  bitten  by  a  rabid  animal  can  escape  having 
the  disease  by  taking  the  kind  of  vaccination  which  is 
called  the  Pasteur  treatment.  You  can  get  information 
about  the  treatment  from  the  boards  of  health  of  the 
states  and  large  cities. 

Sick  Pets.  —  Pet  animals  sometimes  have  the  same 
kinds  of  sickness  that  people  have,  and  persons  may 
catch  the  diseases  by  handling  them.  Many  persons 
have  caught  diphtheria  by  handling  cats  which  had 
the  disease.  If  your  cat,  or  dog,  or  other  pet  animal 
is  sick,  do  not  handle  it  or  leave  it  in  the  house,  but 
give  it  a  good  bed  in  the  woodhouse  or  barn,  and  let  a 
careful  grown  person  take  care  of  it. 


QUESTIONS 

What  are  vermin? 
Name  some  of  the  common  vermin. 
What  harm  do  bee  stings  do  ? 
How  do  house  flies  spread  diseases  ? 
What  diseases  are  often  spread  by  flies  ? 
Where  do  flies  get  the  disease  germs  which  they  carry  on 
their  bodies  ? 

How  may  disease  germs  be  kept  from  the  bodies  of  flies  ? 

GEN.    HYG. 14 


210  VERMIN 

How  can  we  protect  ourselves  against  flies  ? 

Where  are  young  flies  found  ? 

What  is  a  maggot  ? 

How  may  maggots  be  prevented  from  growing  to  winged 
flies? 

What  disease  may  be  caught  from  the  bite  of  a  stable  fly  ? 

How  may  stable  flies  be  destroyed  ? 

What  harm  is  done  by  mosquitoes  ? 

How  can  you  tell  the  kind  of  mosquito  which  produces 
malaria  ? 

What  is  the  cause  of  yellow  fever  ? 

How  may  malaria  and  yellow  fever  be  prevented  ? 

Where  do  young  mosquitoes  live  ? 

How  can  we  get  rid  of  mosquitoes  ? 

What  harm  is  done  by  cockroaches  ? 

How  can  we  get  rid  of  cockroaches  ? 

What  are  lice? 

What  are  wife? 

How  may  lice  and  nits  be  removed  from  the  hair  ? 

What  harm  do  bedbugs  do  ? 

What  harm  is  done  by  fleas  ? 

How  do  fleas  help  to  spread  the  plague  ? 

What  have  rats  to  do  with  the  spread  of  the  plague  ? 

How  can  we  get  rid  of  rats  and  mice  ? 

What  disease  is  often  spread  by  stray  dogs  and  cats  ? 

If  a  person  is  bitten  by  a  cat  or  dog,  what  should  be  done 
with  the  animal  ? 

If  a  person  is  bitten  by  an  animal  that  has  hydrophobia, 
what  should  be  done  to  prevent  him  from  taking  the  disease  ? 

What  harm  might  a  sick  pet  do  to  your  health  ? 


CHAPTER  XX 
FOOD   ELEMENTS 

Definition  of  Food.  —  Food  has  two  uses ;  first, 
to  become  new  flesh,  and  second,  to  be  oxidized  and 
supply  the  body  with  heat  and  power. 

Any  substance  which  may  become  a  part  of  living 
flesh,  or  may  be  safely  oxidized  in  the  body,  is  a  food. 

Foods  are  mixtures  of  protein,  fat,  sugar,  water,  and 
minerals.  These  are  the  same  kinds  of  substances  that 
compose  the  flesh  and  bones  of  the  body  (p.  28). 

Starch  is  a  food  substance  which  is  nearly  like  sugar, 
and  which  is  changed  to  sugar  after  it  has  been  eaten. 
We  may  count  the  starch  in  food  as  sugar.  Starch 
and  sugar  are  often  called  carbohydrates. 

Flesh-forming  Food.  -  -  The  living  cells  of  flesh 
are  composed  principally  of  protein  (p.  29).  The 
body  does  not  make  its  protein  out  of  other  substances, 
but  it  takes  bits  of  protein  from  food  and  adds  them 
to  the  living  flesh.  A  person  doing  light  work  needs 
about  three  ounces  of  protein  each  day  in  order  to 
form  new  flesh  in  the  place  of  that  which  becomes  worn 
out.  A  food  which  contains  a  great  deal  of  protein  is 
called  a  flesh-forming  food.  Examples  of  this  kind  of 
food  are  lean  meat,  eggs,  and  beans. 


212  FOOD   ELEMENTS 

Fuel  Food.  —  Most  of  the  heat  and  power  of  the 
body  comes  from  the  oxidation  of  the  fat  and  sugar 
which  are  contained  in  food.  When  fat  and  sugar  are 
eaten,  they  are  quickly  oxidized,  and  neither  of  them 
becomes  living  flesh.  They  are  like  the  coal  which  is 
burned  in  a  boiler,  but  which  cannot  become  a  part  of 
the  machinery. 

Protein  is  like  the  iron  of  which  the  boiler  and  ma- 
chinery are  made.  But  protein  is  also  a  fuel  food,  for 
worn-out  flesh  is  protein  which  has  been  oxidized 

(P-  173). 

A  food  which  contains  a  great  deal  of  fat,  or  sugar, 
or  starch,  is  called  a  heat-producing  food,  or  a,  fuel  food. 
Examples  of  this  kind  of  food  are  fat  meat,  potatoes, 
and  grain.  But  these  foods  contain  some  protein, 
and  are  also  flesh-forming  foods. 

Water  and  Minerals.  —  Water  and  minerals  are 
needed  in  order  to  carry  on  the  oxidation  and  the  re- 
building of  the  body,  and  yet  they  themselves  do  not 
become  oxidized  or  changed.  They  go  to  every  part 
of  the  body  with  the  other  food  substances,  and  help 
the  flesh  to  make  use  of  the  protein,  fat,  and  sugar. 
Minerals  are  found  in  nearly  all  kinds  of  food,  but  a 
little  salt  is  usually  added  to  food  on  account  of  its 
taste. 

Flavorings.  —  Pepper,  vanilla,  and  other  substances 
are  often  added  to  food  in  order  to  give  it  a  pleasant 
taste.  When  food  which  has  but  little  taste  is  eaten, 
the  body  cannot  make  the  best  use  of  it.  The  use  of 


FOOD   ELEMENTS  213 

flavorings  is  to  help  the  body  to  make  good  use  of  its 
food. 

Taste  is  also  a  great  help  in  judging  the  purity  and 
healthfulness  of  food.  If  food  has  a  bad  taste,  it  is 
usually  not  healthful. 

Waste  Substances  in  Food.  —  The  body  cannot  make 
use 'of  such  things  as  bones,  tough  strings  of  flesh,  the 
seeds  and  skins  of  fruit,  and  the  husks  of  grain.  All' 
foods  contain  some  of  these  waste  substances,  but 
they  form  the  greater  part  of  the  solids  of  some  foods, 
such  as  cabbage  and  turnips.  Yet  foods  which  con- 
tain a  large  amount  of  waste  substances  may  be  useful 
on  account  of  their  taste. 

Alcohol  as  a  Food.  —  Alcohol  cannot  become  flesh. 
It  may  be  oxidized  in  the  body,  and  may  give  off  heat, 
and  therefore  some  persons  would  call  it  a  food.  The 
body  is  not  made  in  such  a  way  that  it  can  oxidize 
alcohol  with  safety.  Using  alcohol  as  a  food  for  the 
body  is  like  using  it  as  fuel  in  a  coal  stove.  We  cannot 
control  the  action  of  alcohol  in  the  body  any  more 
than  we  can  control  its  burning  in  a  coal  stove.  Alcohol 
cannot  be  safely  oxidized  in  the  body,  and  it  is  not  a 
true  food. 

Calorie.  —  We  measure  the  food  value  of  fat,  sugar, 
or  starch  by  the  amount  of  heat  which  the  food  will 
produce  when  it  is  oxidized.  We  may  also  measure 
the  food  value  of  protein  in  the  same  way,  for  nearly 
all  the  protein  which  is  built  into  living  flesh  takes  the 
place  of  other  protein  which  has  been  oxidized.  -A 


214  FOOD  ELEMENTS 

growing  child  takes  a  little  more  protein  than  it  oxidizes 
and  in  that  way  its  body  increases  in  size. 

The  quantity  of  heat  in  a  mass  of  any  substance  is 
measured  by  what  are  called  calories.  One  calorie 
is  very  nearly  the  quantity  of  heat  which  will  warm 
two  quarts  of  water  one  degree  Fahrenheit.  One 
hundred  calories  will  change  one  quart  of  water  from 
freezing  cold  nearly  to  a  boiling  heat.  A  man  doing  very- 
light  work  produces  about  one  hundred  calories  of  heat 
each  hour,  or  about  twenty-four  hundred  calories  in 
a  day.  He  produces  heat  about  as  fast  as  two  burning 
candles,  such  as  are  used  in  lighting  houses. 

If  we  know  how  many  calories  each  kind  of  food  will 
produce,  we  can  reckon  how  much  food  a  person  needs 
to  eat.  If  an  ounce  of  protein,  or  an  ounce  of  sugar, 
is  oxidized,  it  will  yield  about  one  hundred  and  twenty 
calories.  An  ounce  of  fat  will  yield  about  two  hundred 
and  forty  calories. 

If  a  person  should  eat  nothing  but  protein,  his 
body  would  require  about  twenty  ounces  a  day,  or 
about  as  much  as  is  contained  in  the  whites  of 
nine  dozen  eggs,  in  order  to  furnish  the  2400  calories 
that  he  needs.  If  he  should  eat  nothing  but  fat, 
about  ten  ounces  of  butter  would  supply  the  calories 
that  he  needs.  If  he  should  use  only  sugar  for  food, 
he  would  need  about  one  and  a  quarter  pounds  each 
day.  But  he  cannot  live  on  either  kind  of  food  sub- 
stance alone.  A  person  needs  to  eat  a  mixture  of  pro- 
tein, fat,  and  sugar  in  order  to  be  healthy. 


FOOD   ELEMENTS  215 

Amount  of  Food.  —  In  reckoning  what  food  to  eat, 
first  choose  enough  protein  to  replace  that  which  is 
worn  out  and  oxidized  in  the  flesh.  The  amount  of 
protein  which  will  be  needed  is  about  three  ounces  a 
day  (p.  211).  This  quantity  of  protein  will  produce 
three  hundred  and  sixty  calories  of  heat,  which  is 
about  one  sixth  as  much  as  the  body  needs.  The  re- 
maining '2040  calories  could  be  obtained  from  four 
ounces  of  fat  and  nine  ounces  of  sugar,  or  from  two 
ounces  of  fat  and  thirteen  ounces  of  sugar.  A  person 
who  does  hard  work  will  need  much  more  than  these 
amounts  of  food  substances. 

Protein,  3  ounces,  yielding    360  calories 

Fat,         4  ounces,  yielding    960  calories 

Sugar,     9  ounces,  yielding  1080  calories 

2400  calories 

Table  showing  the  food  substances  which  the  body  usually  requires 
in  a  day  and  the  number  of  calories  which  may  be  obtained  from 
them. 

Concentrated  Food.  —  Some  persons  think  that  there 
are  foods  which  are  so  concentrated  and  nourishing 
that  a  teaspoonful  of  them  mixed  with  a  glass  of  water 
will  supply  the  body  with  as  much  food  substance  as 
a  full  meal  of  bread  and  meat.  This  is  not  so.  About 
a  small  teacupful  of  pure,  dried  protein  is  needed  each 
day  in  order  to  rebuild  the  worn-out  flesh,  and  nothing 
else  will  take  the  place  of  that  quantity  of  protein. 

The  most  concentrated  fuel  food  is  butter,  or  lard, 
and  about  a  cupful  of  either  one  is  needed  to  supply 


2i6  FOOD   ELEMENTS 

the  daily  needs  of  the  body.  Two  cupfuls  of  the  purest 
and  most  concentrated  food  is  the  very  least  that  will 
keep  a  person  in  good  health. 

A  tablespoonful  of  meat  extract,  or  beef  tea,  or  pep- 
tonized  food,  does  not  contain  any  more  nourishment 
than  a  tablespoonful  of  milk.  These  substances  may 
have  a  value  as  medicines,  but  they  have  very  little 
food  value.  The  nourishment  in  any  food  consists  in 
its  protein,  fat,  and  sugar  or  starch,  and  these  sub- 
stances must  be  in  quantities  that  are  measured  by  cup- 
"fuls  rather  than  by  spoonfuls. 

Composition  of  Food.  —  If  you  know  the  composi- 
tion of  the  various  foods,  you  can  tell  what  ones  to 
choose  in  order  to  supply  the  needs  of  the  body.  Those 
who  buy  supplies  for  armies  reckon  the  composition 
of  the  food  so  that  they  can  buy  the  right  amounts  of 
protein,  fat,  and  sugar  to  supply  the  needs  of  the 
soldiers.  Farmers  often  choose  the  food  for  their 
cattle  by  means  of  tables  of  the  compositions  of  dif- 
ferent kinds  of  hay  and  grain.  The  table  on  the  fac- 
ing page  shows  the  composition  of  common  foods. 

Balanced  Diet.  —  The  food  which  a  person  eats  is 
called  his  diet.  A  day's  supply  of  food  for  a  man  doing 
very  light  work  will  consist  of  about  three  ounces  of  flesh- 
forming  proteins  and  with  it  so  much  fat  and  sugar  or 
starch  that  the  whole  amount  of  food  will  furnish  about 
twenty-four  hundred  calories  of  heat.  The  flesh- form- 
ing proteins  will  supply  about  one  sixth  of  the  total 
heat,  and  the  fuel  food  will  supply  about  five  sixths. 


FOOD   ELEMENTS 


217 


FOODS 

WATER 

PER 

CENT 

PROTEIN 

PFR 

CENT 

FAT 

PER 

CENT 

SUGAR 

OR 

STARCH 

PER 

CENT 

MINERALS 
PER  CENT 

CALORIES 
IN  EACH 
POUND 

White  flour  .     .     .     ,/.r 
Whole  wheat  flour      .     . 
Corn  meal     

12.5 
II.4 

n.6 

II.  0 
13-8 

8.4 

I.I 
1.9 
4-  7 

74-9 
71.9 
74.  o 

0-5 
I.O 
I  3 

1695 
1700 
1760 

Oatmeal 

7  3 

16  i 

7  2 

67  =: 

I  O 

1870 

Corn  meal  mush  .  .  . 
White  bread  .... 
Rice  boiled 

60.7 
29.9 

72  ^ 

5-5 
8.9 

2  8 

4.8 
4.1 
O  I 

27-5 
56.0 

24.  4. 

i-5 
i.i 

O  2 

825 

1395 
r  2  C 

Dried  lima  beans    . 
Boiled  potatoes      .     .     . 
Tomatoes,  fresh      .     .     . 
Cooked  beets     .... 
Fresh  asparagus     .     .     . 
Green  corn,  kernels     .     . 
Apples,  sliced    .... 
Banana  pulp      .... 
Peaches    .          ... 

10.4 

75-5 
94-3 
88.6 
94.0 

75-4 
84.6 

75-3 

80  4. 

18.1 

2-5 
0.9 

2-3 
1.8 

3-i 
0.4 

i-3 

O  7 

i-S 

O.I 

0.4 

O.I 
0.2 
I.I 

o-5 
0.6 

O  I 

65-9 
2O.9 

3-9 
7-4 
3-3 
19.7 
14.2 

22.O 

9    A 

4.1 
I.O 
0.5 

1.6 

0.7 
0.7 

o-3 
0.8 

O  A. 

*)zo 
l665 

455 
105 
190 

105 
480 
300 
470 

TQ  r 

Peanut,  kernels  .  .  . 
Roast  beef 

9.2 

J.8  2 

25.8 

22   1 

38.6 

28  2 

24.4 
O  O 

2.0 
I    3 

Ayj 
2440 

T  COO 

Lean  ham,  cooked  .  . 
Dried  beef  
Chicken  meat  .... 
Fresh  codfish  .... 
Salt  codfish  .  .  .  .  . 

60.0 

44.8 

74-8 
80. 
c?  c 

25.0 

39- 
21-5 
18.5 

21     S 

10.0 

5. 

2.5 

o-5 

O  3 

0.0 
0.0 
0.0 
0.0 

o  o 

X'O 

5-o 

II.  2 
1.2 
I.O 

24.  7 

865 
940 
500 

365 

4.2O 

Cooked  bluefish  .  .  . 
Canned  crab  meat  .  . 
Hen's  eggs 

68.2 
80.0 

737 

26.1 

16.5 

14  o 

4-5 
i-5 

1  1  O 

0.0 

o.o 
o  o 

1.2 
2.0 
I  O 

670 

375 

Oyster  meat  .... 
Cow's  milk  .... 

/  0'  / 

88.3 

87  o 

6.0 

•3    -2 

i-3 
40 

3-3 
50 

I.I 

O  7 

230 

-2  T  cr 

Cream  cheese  .... 
Butter  .... 

34-2 

II  O 

25-9 

I  O 

33-7 
gc  o 

2.4 
o  o 

3-8 
30 

o^o 
1850 

3285; 

Sponge  cake  .... 
Custard  pie  . 

153 

62  A. 

6.3 

42 

10.7 
6  3 

65.9 

26  I 

.v-» 

1.8 

I  O 

o^°o 

1795 
821; 

w-j 

°^D 

Table  showing  the  composition  of  common  foods,  and  the  num- 
ber of  calories  produced   by  their  oxidation. 


218  FOOD   ELEMENTS 

A  diet  in  which  protein  supplies  about  one  sixth  of  the 
heat  and  energy  is  called  a  balanced  diet. 

Some  foods  contain  a  great  deal  of  flesh-forming 
substances,  and  only  small  quantities  of  substances  that 
are  heat-producing.  Examples  of  these  kinds  of  food 
are  lean  meat  and  the  whites  of  eggs.  Other  foods 
consist  mostly  of  heat-producing  substances.  Ex- 
amples of  these  kinds  of  food  are  potatoes  and  rice. 
A  mixture  of  meat  and  potatoes  would  make  a  balanced 
diet,  for  each  has  an  abundance  of  what  the  other 
lacks. 

Most  vegetable  foods  contain  a  great  deal  of  sugar 
or  starch,  and  only  a  small  quantity  of  protein  and 
fat.  Most  animal  foods  contain  a  great  deal  of  pro- 
tein and  fat,  and  almost  no  sugar  or  starch.  A  mixture 
of  vegetable  and  animal  foods  will  usually  form  a  bal- 
anced diet. 

The  Arithmetic  of  Dieting.  —  The  following  examples 
show  how  we  may  calculate  the  value  of  a  food. 

Example  i .  How  many  calories  will  a  pound  of  wheat 
bread  produce  ? 

From  the  table  on  p.  217  we  find  that  bread  is  8.9 
per  cent  protein,  4.1  per  cent  fat,  and  56.0  per  cent 
starch.  The  number  of  ounces  of  protein  in  a  pound 
of  bread  is  16  times  0.089,  or  z-4  ounces.  The  number 
of  calories  which  the  protein  will  produce  is  1.4  times 
120,  or  1 68  calories. 

The  number  of  ounces  of  fat  in  a  pound  of  bread  is 
16  times  0.041,  or  0.65  ounce.  The  number  of  calories 


FOOD   ELEMENTS  219 

which  the  fat  will  produce  is  0.65  times  240,  or  156 
calories. 

The  number  of  ounces  of  starch  in  a' pound  of  bread 
is  1 6  times  0.56,  or  8.96.  The  number  of  calories  in 
the  starch  is  8.96  times  120,  or  1075  calories. 

The  total  number  of  calories  in  a  pound  of  bread  is 
therefore  168  +  156  +  1075,  or  1399  calories. 

In  like  manner  the  number  of  calories  given  in  the 
last  column  of  the  table  on  p.  217  may  be  calculated 
for  each  kind  of  food. 

Example  2.  If  a  person  were  to  live  on  bread  alone, 
how  much  would  he  need  in  a  day  ? 

We  first  calculate  how  much  bread  he  should  take 
in  order  to  get  three  ounces  of  protein  a  day.  From 
the  table  on  p.  217  we  find  that  about  one  eleventh 
of  bread  is  protein.  In  order  to  get  three  ounces  of 
protein,  thirty-three  ounces  of  bread,  or  about  two 
pounds,  will  be  needed.  This  is  about  a  loaf  and  a  half. 

By  looking  at  the  table  on  p.  217  we  find  that  a 
pound  of  bread  will  produce  about  1395  calories.  Two 
pounds,  therefore,  produce  2790  calories,  which  is 
slightly  more  than  the  body  needs.  If  the  amount  of 
bread  is  lessened  so  as  to  produce  2400  calories,  the 
quantity  of  protein  will  be  lessened  to  about  two  and 
one  half  ounces,  which  is  too  little  for  the  daily  needs 
of  the  body.  Bread  alone  is,  therefore,  not  a  perfectly 
balanced  diet. 

Example  3.  If  a  person  were  to  live  on  bread  and 
butter,  how  much  would  he  need  in  a  day  ? 


220  FOOD   ELEMENTS 

If  butter  is  spread  rather  thin,  it  will  weigh  about 
one  tenth  as  much  as  the  bread.  The  thirty-three 
ounces  of  bread  given  in  Example  i  will  have  about 
three  and  one  half  ounces  of  butter  on  it.  From  the 
table  on  p.  217  we  find  that  a  pound  of  butter  con- 
tains almost  no  protein,  but  it  produces  3285  calories. 
Therefore,  three  and  one  half  ounces  of  butter  will 
produce  718  calories.  The  total  number  of  calories 
produced  by  the  thirty-three  ounces  of  bread  and  the 
three  and  one  half  ounces  of  butter  will  be  3508  calories. 

The  proper  number  of  calories,  or  2400,  will  be  ob- 
tained from  two  thirds  of  thirty-three  ounces  of  bread, 
or  twenty- two  ounces,  and  two  thirds  of  three  and  one 
half  ounces  of  butter,  or  about  two  and  one  half  ounces. 
But  in  this  quantity  of  bread  and  butter,  there  are  only 
two  ounces  of  protein,  which  is  only  two.  thirds  as 
much  as  the  body  needs.  A  bread  and  butter  diet 
is  therefore  not  well  balanced. 

Example  4.  If  a  person  were  to  live  on  ham  sand- 
wiches, how  much  would  he  need  in  a  day  ? 

From  Example  3,  we  find  that  thirty-three  ounces 
of  bread,  spread  with  butter,  will  contain  three  ounces 
of  protein,  and  will  produce  3508  calories.  About  half 
a  pound  of  lean  boiled  ham  sliced  thin  will  be  used 
in  making  the  bread  and  butter  into  sandwiches.  From 
the  table  on  p.  217  we  can  reckon  that  the  ham 
will  contain  about  two  ounces  of  protein,  and  will 
produce  about  432  calories.  The  sandwiches  will 
therefore  contain  five  ounces  of  protein,  and  will  pro- 


FOOD   ELEMENTS  221 

duce  3940  calories.  Three  fifths  of  the  sandwiches 
will  contain  three  ounces  of  protein,  and  will  produce 
about  2400  calories.  Sandwiches,  therefore,  make  a 
well-balanced  diet,  and  about  one  loaf  of  bread,  made 
into  ham  sandwiches,  is  sufficient  food  for  one  person 
for  a  day. 

QUESTIONS 

Give  a  definition  of  food. 

What  are  the  uses  of  food  ? 

What  are  the  five  useful  substances  which  compose  foods  ? 

What  substances  does  a  flesh-forming  food  contain  ? 

What  substances  do  heat-producing  foods  contain  ? 

What  foods  contain  mineral  substances  ? 

Name  some  of  the  waste  substances  which  are  contained  in 
food. 

Give  a  reason  why  alcohol  might  be  called  a  food. 

Give  some  reasons  why  alcohol  is  not  called  a  true  food. 

How  much  protein  does  a  person  need  to  eat  each  day  ? 

What  is  a  calorie? 

How  many  calories  of  heat  does  the  body  need  to  produce  in 
a  day? 

How  many  calories  does  an  ounce  of  protein  produce?  an 
ounce  of  fat  ?  an  ounce  of  sugar  ?  an  ounce  of  starch  ? 

Why  is  a  teaspoonful  of  concentrated  food  a  day  not  suf- 
ficient for  a  man  ? 

What  is  a  balanced  diet? 

Choose  a  day's  supply  of  food  which  would  form  a  balanced 
diet. 

Look  at  the  table  on  p.  217  and  reckon  how  much  potatoes 
and  fresh  codfish  a  person  will  need  in  a  day  if  he  uses  no  other 
food. 


CHAPTER  XXI 
DIGESTION 

Changes  produced  by  Digestion.  -  -  There  are  many 
different  forms  of  protein,  fat,  and  sugar,  but  only  one 
form  of  each  can  enter  the  blood  and  be  of  use  to  the 
various  parts  of  the  body.  These  forms  of  protein,  fat, 
and  sugar  are  seldom  found  in  food  before  it  is  eaten, 
but  they  are  produced  by  changes  which  take  place  in 
food  after  it  has  been  swallowed.  Changing  food  which 
has  been  eaten  to  forms  which  can  enter  the  blood  is 
called  digestion. 

Digestion  changes  all  kinds  of  protein  to  a  form 
which  is  usually  called  peptone.  It  changes  starch  and 
sugar  to  a  form  of  sugar,  called  grape  sugar.  It  divides 
fat  into  fine  drops  which  float  in  water,  forming  a 
milky  liquid  called  an  emulsion.  The  water  and  min- 
erals of  food  are  not  digested,  but  enter  the  blood  in 
the  form  in  which  they  are  eaten. 

Organs  of  Digestion.  —  Food  is  digested  in  a  tube 
which  begins  at  the  mouth,  and  extends  the  whole 
length  of  the  trunk  of  the  body.  The  part  of  the  diges- 
tive tube  just  back  of  the  mouth  is  called  the  pharynx, 
and  the  next  part  of  the  tube  is  called  the  esophagus. 
The  pharynx  is  a  muscular  box  which  squeezes  food  into 


DIGESTION  223 

the  esophagus  at  the  beginning  of  an  act  of  swallowing. 
The  esophagus  conducts  the  food  into  the  stomach. 

The  stomach  is,  so  much  larger  than  the  rest  of  the 
digestive  tube  that  it  looks  like  a  bag  between  the  ends 
of  two  smaller  tubes.  It  is  composed  of  muscle,  and 
holds  about  two  quarts.  It  lies  crosswise  of  the  body, 
mostly  on  the  left  side  between  the  ribs  and  the  waist- 
line. 

The  part  of  the  digestive  tube  which  is  next  to  the 
stomach  is  called  the  intestine.  It  is  a  thin,  muscular 
tube,  somewhat  larger  than  a  person's  thumb,  and  about 
five  times  as  long  as  his  body.  It  lies  in  coils  and  nearly 
fills  the  lower  part  of  the  trunk  of  the  body.  Another 
name  for  the  intestine  is  the  bowel.  The  lower  fifth  of 
the  intestine  is  two  or  three  times  as  large  as  the  upper 
four  fifths,  and  is  called  the  large  intestine. 

Fluids  of  Digestion.  —  The  body  digests  food  by  dis- 
solving it  in  liquids  which  are  in  the  mouth,  the  stomach, 
and  the  intestine. 

The  liquid  in  the  mouth  is  called  the  saliva.  Its 
work  is  to  change  starch  to  grape  sugar.  It  is  pro- 
duced by  six  organs  called  the  salivary  glands.  Two  of 
them  lie  in  front  of  the  ears,  two  under  the  sides  of  the 
lower  jaw,  and  two  under  the  front  part  of  the  tongue. 
These  glands  are  swollen  during  the  sickness  called  the 
mumps. 

The  digestive  fluid  in  the  stomach  is  called  the 
gastric  juice.  Its  work  is  to  change  protein  to  peptone. 
It  is  poured  out  by  the  lining  of  the  stomach  in  the  same 


224 


DIGESTION 


way  that  perspiration  is  poured  out  by  the  skin.  It  is 
formed  in  thousands  of  tiny  glands  which  stand  side 
by  side,  like  pin  pricks,  in  the  mucous  membrane  of 
the  stomach. 

The  fluids  of  the  intestine  are  the  intestinal  juice, 
the  pancreatic  juice,  and  the  bile.  The  intestinal  juice 

is  produced  by  glands 
which  lie  in  the  mucous 
membrane  of  the  intes- 
tine, and  which  are  like 
the  glands  in  the  stom- 
ach. 

The  pancreas  is  a 
large  gland  which  lies 
behind  the  stomach.  It 
manufactures  a  liquid, 
called  the  pancreatic 
juice,  which  it  sends 
into  the  upper  part  of 
the  intestine  through  a 
small  tube. 

The  liver  is  a  large 
gland  which  lies  under  the  ribs  on  the  right  side  of 
the  body.  It  produces  a  bitter,  yellow  liquid,  called 
the  bile, .which  flows  into  the  intestine  through  the 
same  tube  that  the  pancreatic  juice  flows  through. 

The  work  of  the  mixture  of  liquids  in  the  intestine 
is  to  change  starch  and  sugar  to  grape  sugar,  and  pro- 
tein to  peptone,  and  to  make  fats  into  an  emulsion. 


Gastric  glands. 


DIGESTION  225 

Thus  the  mouth  begins  the  digestion  of  starch,  the 
stomach  begins  the  digestion  of  protein,  and  the  in- 
testine digests  all  kinds  of  food. 

Time  Required  for  Digestion.  —  Digestion  begins 
almost  as  soon  as  food  enters  the  mouth,  and  some  of 
the  food  is  ready  to  enter  the  blood  within  ten  minutes 
after  it  has  been  swallowed.  The  stomach  will  usually 
be  empty  in  about  three  hours  after  eating,  but  the 
digestion  of  food  will  continue  for  about  six  hours  in 
the  intestine. 

Peristalsis.  —  The  greater  part  of  the  flesh  of  the 
esophagus,  stomach,  and  intestine  consists  of  involun- 
tary muscle  (p.  76).  The  use  of  the  muscle  is  to  force 
the  food  down  the  digestive  tube.  It  contracts  in 
ring-like  waves  which  run  down  the  esophagus,  stomach, 
and  intestine,  and  force  the  food  forward,  just  as  if 
each  wave  were  a  ring  running  slowly  down  the  di- 
gestive tube.  This  motion  is  called  peristalsis.  When 
food  reaches  any  part  of  the  digestive  tube,  peristalsis 
begins  in  that  part,  and  the  motion  of  the  part  usually 
stops  as  soon  as  food  has  passed  it. 

The  stomach  and  intestine  force  the  food  onward  with 
a  slow  and  gentle  motion  that  is  not  usually  felt.  But 
if  the  wrong  kind  of  food  is  eaten,  the  muscles  may  act 
rapidly  and  forcibly  in  order  to  push  the  harmful  food 
out  of  the  body.  The  peristalsis  then  causes  the  kind 
of  pain  which  is  called  stomach  ache. 

When  a  harmful  kind  of  food  is  swallowed,  the  waves 
of  peristalsis  sometimes  run  backward  and  force  the 

GEN.    HYG. 15 


226  DIGESTION 

food  back  into  the  mouth.  This  backward  motion  of 
food  into  the  mouth  is  called  vomiting. 

Exercise  during  Digestion.  —  Digesting  food  re- 
quires the  muscles  of  the  stomach  and  intestine  to  work. 
If  you  exercise  or  study  hard  near  a  mealtime,  you  may 
use  up  your  strength,  and  may  not  have  strength  left 
to  digest  your  food  properly.  Take  a  few  moments  for 
rest  after  each  meal. 

Bacteria  in  the  Intestine.  —  The  intestine  contains 
great  numbers  of  living  bacteria  which  are  very  much 
like, the  bacteria  of  decay  outside  of  the  body.  They 
live  upon  that  part  of  food  which  does  not  become 
digested,  and  as  they  grow,  they  cause  the  food  to 
decay.  The  food  is  then  as  poisonous  as  it  would  have 
been  if  it  had  been  spoiled  when  it  was  eaten.  Most 
of  the  bad  feelings  which  are  caused  by  poor  digestion 
are  due  to  the  decay  of  undigested  food. 

Chewing  Food.  —  No  one  can  control  the  digestion 
of  food  in  the  stomach  and  intestine,  but  the  way  in 
which  a  food  is  eaten  has  a  great  deal  to  do  with  the 
way  in  which  it  will  be  digested.  If  a  food  is  eaten 
properly,  it  will  usually  be  digested  readily. 

Grinding  food  to  small  bits  in  the  mouth  helps  all 
the  digestive  fluids  to  dissolve  it.  A  great  deal  of  poor 
digestion  comes  from  swallowing  food  in  lumps  which 
are  too  big  for  the  digestive  juices  to  dissolve  easily. 
Chewing  food  is  one  of  the  most  important  steps  in 
digestion,  for  it  breaks  the  food  into  small  pieces  which 
the  stomach  and  intestine  can  easily  digest. 


DIGESTION  227 

Mouth  Digestion.  —  Another  object  of  chewing  food 
is  to  mix  it  with  saliva.  Each  mouthful  of  food  does 
not  remain  in  the  mouth  long  enough  for  much  of  its 
starch  to  be  digested  then,  but  the  saliva  continues  to 
act  for  about  half  an  hour  after  the  food  reaches  the 
stomach.  About  half  of  the  work  of  digesting  starch 
to  sugar  may  be  done  by  the  saliva,  if  food  is  eaten 
slowly. 

The  main  part  of  the  food  usually  eaten  is  starch. 
If  starch  is  not  digested  by  saliva,  the  intestine  has  to 
do  double  its  own  share  of  work  to  digest  it.  The  food 
will  then  not  digest  well,  and  it  will  be  the  cause  of 
headaches  and  stomach  aches.  If  you  chew  soft  food, 
such  as  oatmeal,  long  enough  to  mix  it  with  saliva,  you 
will  help  the  stomach  and  intestine  to  digest  it. 

Eating  Fast.  —  When  you  eat  fast,  you  cannot  chew 
your  food  well,  or  mix  it  with  saliva.  The  stomach  and 
intestine  cannot  do  the  work  which  the  mouth  should 
have  done.  If  your  food  is  not  well  digested  in  the 
mouth,  a  large  part  of  it  will  escape  digestion  in  the 
stomach  and  intestine.  You  will  get  no  more  nourish- 
ment from  a  large  quantity  of  food  eaten  fast,  than 
from  a  small  quantity  eaten  slowly.  A  little  food  well 
digested  is  better  than  a  great  deal  half  digested.  If 
you  have  only  five  minutes  for  eating,  you  will  get  about 
as  much  nourishment  by  eating  slowly  as  by  eating 
fast  during  that  time.  You  cannot  chew  all  your  food 
well  if  you  take  less  than  fifteen  minutes  in  eating  a 
meal. 


228  DIGESTION 

Drinking  at  Mealtimes.  —  Some  kinds  of  foods,  such 
as  soup,  contain  a  great  deal  of  water,  and  other  kinds, 
such  as  crackers,  are  very  dry;  yet  you  can  easily 
digest  both  kinds.  Taking  water  with  a  meal  does  not 
interfere  with  the  digestion  of  food.  You  may  safely 
drink  water,  or  tea,  or  coffee  with  a  meal,  if  you  are 
thirsty.  But  drinking  water  in  order  to  be  able  to 
swallow  food  rapidly  is  harmful  to  the  digestive  organs. 

A  very  cold  drink  with  a  meal  stops  the  action  of 
the  digestive  juices  until  the  water  becomes  warm. 
Hot  drinks  destroy  the  gastric  juice,  and  prevent  it 
from  acting  at  all.  Ice  water  and  very  hot  drinks  are 
both  harmful  to  digestion. 

Eating  between  Meals.  —  The  muscles  of  the 
stomach  and  intestine  become  tired  and  need  a  rest, 
as  the  muscles  of  the  arm  do.  The  cells  of  the  glands 
which  produce  the  digestive  juices  also  need  to  rest 
often.  It  is  best  to  eat  only  at  mealtimes,  so  that  the 
stomach  and  intestine  may  have  time  to  rest  between 
meals. 

How  much  to  Eat.  —  The  feeling  of  hunger  is  a  nat- 
ural guide  by  which  you  can  tell  when  to  eat,  and  how 
much  food  to  take.  Hunger  is  usually  a  safe  guide  if 
you  eat  slowly  and  chew  your  food  well.  But  your 
hunger  and  your  appetite  will  often  lead  you  to  eat 
wrongly  if  you  eat  rapidly  or  if  you  take  food  for  the 
sake  of  its  taste,  or  for  the  pleasure  of  eating.  If  you 
eat  slowly  and  only  at  mealtime,  you  may  safely  eat 
enough  to  satisfy  your  natural  hunger  and  appetite. 


DIGESTION  229 

The  Feelings  and  Digestion. --Your  feelings  have 
a  great  deal  to  do  with  the  digestion  of  food.  When 
you  are  hungry,  the  sight  and  smell  of  good  food  causes 
the  saliva  to  flow  into  the  mouth.  If  you  enjoy  the 
taste  of  food,  the  gastric  juice  will  begin  to  flow  into 
the  stomach  as  soon  as  you  begin  to  eat.  But  if  you 
eat  when  you  have  no  desire  for  food,  or  if  the  food  has 
an  unpleasant  taste,  or  if  you  are  sad  or  angry,  neither 
the  saliva  nor  the  gastric  juice  will  flow  properly,  and 
your  food  will  not  be  well  digested. 

Politeness  and  good  manners  at  table  are  great  aids 
to  digestion,  for  they  make  you  happy  and  help  you 
to  enjoy  your  food.  Other  things  which  will  help  you 
to  digest  your  food  are  good  cooking,  clean  dishes,  and 
pleasant  conversation. 

Rules  for  Eating.  -  -  Your  stomach  and  intestine 
will  usually  digest  all  the  food  that  you  need  if  you  eat 
it  properly.  Most  persons  who  have  indigestion  have 
brought  the  sickness  on  themselves  by  eating  either 
too  rapidly,  or  too  much, -or  too  often.  Their  indiges- 
tion will  usually  stop,  and  their  digestive  organs  will 
nearly  always  do  their  work  well  again,  if  they  eat 
properly. 

It  is  not  hard  to  learn  to  eat  properly.  The  rules  of 
good  table  manners  are  merely  rules  for  eating  in  a 
healthful  way.  That  is,  it  is  good  manners  to  eat 
slowly,  to  chew  the  food  well,  to  be  cheerful  at  the 
table,  and  to  follow  all  the  other  rules  of  healthful 
eating. 


230  DIGESTION 

QUESTIONS 

What  is  digestion? 

What  changes  does  digestion  produce  in  protein?  in  sugar 
and  starch  ?  in  fat  ?  in  water  ?  in  minerals  ? 

Name  the  principal  organs  of  digestion. 

Describe  the  stomach. 

Describe  the  intestine. 

What  is  the  saliva? 

What  changes  in  food  are  produced  by  digestion  in  the 
mouth  ? 

What  is  the  gastric  juice? 

How  is  the  gastric  juice  formed  ? 

What  changes  does  the  gastric  juice  produce  in  food  ? 

What  fluids  digest  food  in  the  intestine  ? 

In  what  organs  is  starch  digested  ?  protein  ?  fat  ? 

What  is  peristalsis  ? 

How  much  time  is  required  for  mouth  digestion?  for 
stomach  digestion  ?  for  digestion  in  the  intestine  ? 

What  effects  are  produced  by  bacteria  growing  in  the  in- 
testine ? 

How  does  chewing  food  well  assist  the  stomach  and  intestine 
to  digest  food  ? 

Why  is  it  necessary  to  chew  soft  foods,  such  as  oatmeal  ? 

Give  some  reasons  why  you  should  eat  slowly. 

What  way  of  drinking  at  a  mealtime  is  harmful  ? 

Why  is  eating  between  meals  harmful  ? 

How  can  you  know  how  much  to  eat  ? 

In  what  respect  are  the  rules  of  good  table  manners  also  good 
rules  for  healthful  eating  ? 


CHAPTER   XXII 
ABSORPTION  AND   ASSIMILATION 

Absorption  of  Food.  —  Digested  food  is  a  whitish 
liquid  which  looks  like  thin  cream.  It  is  mixed  with 
the  indigestible  parts  of  the  food  and  with  many 
waste  matters  of  the  body.  It  is  of  no  use  to  the  body 
until  after  it  has  passed  into  the  blood.  Taking 
digested  food  into  the  blood  is  called  absorption. 

A  large  quantity  of  blood  flows  through  a  network 
of  capillaries  which  lie  very  near  the  surface  of  the 
mucous  membrane  of  the  intestine.  All  that  separates 
the  food  from  the  blood  is  a  thin  partition  composed 
of  a  single  layer  of  epithelial  cells  and  the  thin  walls  of 
the  capillaries.  This  partition  is  as  thin  as  tissue  paper, 
and  allows  water,  minerals,  and  digested  protein  and 
sugar  to  pass  through  it  readily  and  enter  the  blood 
stream.  The  substances  then  pass  through  the  veins 
to  the  liver,  and  then  to  the  heart. 

Osmosis.  -  -  The  mingling  of  unlike  liquids  which 
are  separated  by  a  thin  partition  through  which  they 
may  pass  is  called  osmosis.  The  absorption  of  digested 
food  into  the  blood  is  an  example  of  osmosis.  The 
following  experiment  will  illustrate  the  process :  - 

231 


232 


ABSORPTION   AND   ASSIMILATION 


Carefully  remove  some  of  the  shell  from  the  large 
end  of  an  egg,  taking  care  not  to  break  the  thin  mem- 
brane which  lines  the  shell.  Set  the  broken  end  of 
the  egg  into  a  small  glass  of  water,  and  make  a  small 

hole  through  both  the 
shell  and  the  lining  in 
the  upper  end.  A 
large  amount  of  water 
will  pass  into  the  egg, 
and  will  cause  the 
white  of  the  egg  to 
overflow  through  the 
upper  hole  within  fif- 
teen minutes.  The 
force  which  causes 
water  to  flow  through 
the  membrane  and 
into  the  egg  is  that  of 
osmosis.  A  small 
quantity  of  substance 


An  egg  prepared  to  illustrate  osmosis. 


from  the  egg  will  also 
pass  into  the  water, 
but  it  will  be  much  less  than  the  amount  of  water 
which  passes  into  the  egg. 

Osmosis  in  the  Intestine.  -  -  The  epithelial  cells  of 
the  intestine  and  the  walls  of  the  capillaries  form  a 
thin  membrane  which  is  like  the  lining  of  the  eggshell. 
The  force  which  causes  digested  food  to  pass  through 
the  membrane  into  the  blood  is  that  of  osmosis.  When 


ABSORPTION  AND   ASSIMILATION  233 

food  is  eaten,  very  little  of  it  is  in  a  form  which  can 
pass  into  the  blood.  One  of  the  principal  effects  of 
digestion  is  to  change  food  to  forms  that  may  readily 
pass  into  the  blood  by  the  process  of  osmosis. 

In  some  forms  of  poisoning,  as  that  from  decayed 
meat,  the  poisonous  substances  cause  the  direction  of 
the  flow  in  osmosis  to  be  from  the  blood  into  the  in- 
testine. When  this  occurs,  there  is  usually  severe  sick- 
ness and  pain. 

Other  Examples  of  Osmosis.  —  The  exchange  of 
oxygen  and  carbon  dioxide  in  the  air  sacs  of  the  lungs, 
and  of  oxygen  and  waste  substances  between  the 
capillaries  and  the  cells  of  the  body,  are  examples  of 
osmosis. 

Work  of  the  Liver.  — The  cells  of  the  liver  remove 
the  harmful  substances  which  may  have  entered  the 
blood  with  the  food.  They  also  take  some  kinds  of 
excretions  from  the  blood.  The  mixture  of  waste 
substances  and  excretions  is  the  bile.  If  a  person's 
liver  does  not  do  its  work  well,  he  will  feel  dull  and  sick, 
and  will  have  what  doctors  used  to  call  biliousness. 
Eating  a  great  deal  of  sweet  food  is  a  common  cause 
of  biliousness. 

Absorption  of  Fat.  —  Fat  does  not  soak  through  the 
lining  of  the  intestine  in  the  way  that  oil  soaks  through 
paper,  but  it  passes  through  the  living  cells  of  the 
epithelium  in  tiny  drops.  The  cells  do  not  pass  the 
absorbed  fat  into  the  capillaries,  but  into  lymph  tubes, 
called  lacteals.  The  lacteals  unite  in  a  large  tube, 


234 


ABSORPTION  AND   ASSIMILATION 


called  the  thoracic  duct,  which  conducts  the  digested 
fat  into  a  large  vein  near  the  heart. 

.  Villi.  -  -  The  mucous  membrane 

of  the  intestine  is  covered  with 
tiny  projections,  called  villi,  which 
look  like  the  short  threads  on 
velvet.  Each  villus  contains  a 
lacteal,  and  a  great  number  of 
capillaries.  The  villi  are  like  tiny 
fingers.  They  extend  into  the 
liquid  food  and  take  it  up  quickly. 
What  the  Body  does  with  Food. 
-  Putting  digested  food  to  use 
throughout  the  body  is  called  as- 
similation. The  blood  carries  a 
stream  of  digested  food  to  every 
living  part.  Flesh  that  has  lost 
some  of  its  substance  by  oxidation 
takes  up  protein,  minerals,  and  water,  and  repairs  itself 
with  them.  Glands  take  what  they  need  in  order  to 
form  their  juices.  Muscles  take  up  sugar  and  fat,  and 
oxidize  them  to  produce  heat  and  power.  Each  part 
of  the  body  takes  the  substances  which  it  needs. 

Overeating.  —  The  cells  of  the  body  will  not  use 
more  food  than  they  need,  even  though  the  blood 
brings  a  large  quantity  of  food  to  them.  Overeating 
may  cause  the  body  to  store  up  great  quantities  of 
fat,  but  the  fat  is  a  weight  which  is  often  a  burden 
instead  of  a  help. 


ABSORPTION  AND   ASSIMILATION  235 

The  cells  of  the  body  cannot  use  more  food  than  they 
can  oxidize.  If  a  person  sits  still,  or  does  very  light 
work,  he  takes  t>nly  a  small  quantity  of  oxygen  into 
his  body,  and  oxidizes  only  a  small  amount  of  food. 
If  the  blood  takes  up  more  food  than  the  body  can 
oxidize,  some  of  the  food  will  be  half  oxidized.  The 
excretions  will  then  be  poisonous,  and  will  cause  head- 
aches, rheumatic  pains,  biliousness,  and  kidney  diseases. 
One  of  the  principal  causes  of  these  forms  of  sickness 
is  overeating.  If  you  suffer  from  the  effects  of  over- 
eating, the  cure  is  either  to  eat  only  a  little  food  for 
a  few  days,  or  to  take  a  great  deal  of  exercise,  in  order 
to  oxidize  the  extra  food  in  your  blood. 

Growing  Fat.  --  Thin  persons  often  try  to  grow  fat 
by  eating  all  that  they  can.  This  will  not  always  make 
them  fat,  for  the  food  may  not  be  digested,  and  the 
cells  of  the  body  may  not  make  use  of  that  which  has 
been  digested.  But  many  persons  gain  flesh  when 
they  eat  less  food  than  usual,  and  eat  it  properly, 
for  the  food  may  then  be  well  digested,  and  the  cells 
may  get  the  right  kinds  and  amounts  of  food  that  they 
need. 

Growing  Thin.  —  A  stout  person  can  get  rid  of  his 
fat  by  eating  so  little  food  that  his  body  has  to  oxidize 
its  fat.  In  order  to  get  rid  of  ten  pounds  of  fat  in  a 
month,  a  person  must  oxidize  about  five  ounces  of  fat 
each  day.  Five  ounces  of  fat  will  produce  1 200  calories 
of  heat,  or  about  half  the  heat  which  a  man's  daily  food 
produces  (p.  214).  If  a  person  eats  only  half  as  much 


236  ABSORPTION  AND   ASSIMILATION 

food  as  he  requires,  his  body  will  oxidize  its  fat,  and  he 
will  become  thin. 

Another  way  of  getting  rid  of  the  fat  in  the  body 
is  to  take  a  great  deal  of  hard  exercise  in  order  to  com- 
pel the  body  to  oxidize  its  fat. 

What  becomes  of  Undigested  Food.  --The  parts  of 
food  which  are  not  digested  are  slowly  forced  along  the 
intestine,  and  are  finally  expelled  from  it.  The  in- 
testine also  expels  the  bile  and  other  excretions  which 
the  liver  has  taken  from  the  blood.  Expelling  waste 
matters  and  undigested  food  is  the  last  act  of  digestion, 
and  is  as  important  to  health  as  eating. 

Some  foods,  such  as  vegetables  and  brown  bread, 
contain  strings  and  fibers  which  are  like  wood,  and 
which  do  not  become  digested  or  decayed  in  the  in- 
testine. Harmless  indigestible  substances  like  these 
are  necessary  for  health,  for  they  help  the  peristalsis 
of  the  intestine. 

QUESTIONS 

What  is  absorption? 

What  are  mill? 

How  does  digested  food  pass  into  the  blood  ? 

What  is  osmosis? 

How  can  you  illustrate  the  process  of  osmosis  ? 

What  does  the  liver  do  to  food  after  it  is  absorbed  ? 

What  is  the  bile? 

Describe  the  absorption  of  fat. 

Where  is  fat  taken  after  it  is  absorbed  ? 

What  is  assimilation? 


ABSORPTION  AND   ASSIMILATION  237 

What  does  the  body  do  with  food  after  it  is  absorbed  ? 
What  are  some  of  the  bad  effects  of  overeating  ? 
How  can  a  thin  person  become  f at  ? 
How  can  a  fat  person  become  thin  ? 

Why  is  some  food  which  cannot  be  digested  necessary  for 
health?       - 


CHAPTER   XXIII 
FOODSTUFFS 

Cost  of  Food.  —  A  simple  way  of  supplying  ourselves 
with  food  would  be  to  go  to  a  market  and  buy  pure 
protein,  fat,  sugar,  and  starch,  and  then  mix  them  in 
the  proper  quantities.  But  no  one  does  this,  for  the 
mixtures  which  are  made  from  the  pure  elements  are 
nearly  always  tasteless  and  unwholesome.  Our  di- 
gestive organs  need  those  mixtures  of  food  elements 
which  grow  naturally  in  plants  and  animals. 

The  valuable  parts  of  any  food  are  the  protein,  fat, 
sugar,  and  starch  that  are  in  them.  Sugar  and  starch 
may  be  bought  for  about  six  cents  a  pound,  and  fat 
for  about  twelve  cents  a  pound.  The  cheapest  protein 
costs  about  thirty  cents  a  pound.  If  a  food  costs  more 
than  these  prices,  the  extra  price  is  for  its  taste  and 
appearance,  and  not  for  its  flesh-forming  or  fuel  value. 
The  grains  have  the  greatest  food  value  of  all  foods, 
and  yet  they  cost  the  least.  They  are  also  foods  which 
a  person  can  eat  day  after  day  without  tiring  of  them. 

Oatmeal,  ij  Ib.  @  5  cents     . $0.06 

Corn  meal,  2\  Ib.  @  3  cents      .     .     .     .     .     .    ,     .  0.07 

Beans,  i  Ib.  @  8  cents      .    .     .     ...     .    '.     .     .     .  0.08 

Potatoes,  8  Ib.  @  i  cent    .    .    .     .    .     .     .     .     .     .  0.08 

238 


FOODSTUFFS  239 

Cheese,  f  Ib.  @  16  cents        $0.12 

Salt  codfish,  i  Ib.  @  15  cents    .     .                   ...  0.15 

White  bread,  2  Ib.  @  6  cents 0.12 

Fresh  codfish,  r*lb.  @  14  cents       .     .     .     .    .     .    .  0.14 

Beef,  dried,  \  Ib.  @  40  cents      .     .     .     .     .     .    v.   :.  0.20 

Beef,  round,  i  Ib.  @  20  cents 0.20 

Hen's  eggs,  i  doz.  @  20  cents    .    . .  '  '.    ...   .     ...  0.20 

Cow's  milk,  3  quarts  @  8  cents   '».-.,    .     .     .     .  0.24 

Chicken  meat,  i  Ib.  @  30  cents      .     .     .     ...     .  0.30 

Beets,  10  Ib.  @  5  cents      .     .     .     .     .     .     *     .  ~  .     .  0.50 

Oysters,  3  pints  @  20  cents .  0.60 

Bananas,  5  doz.  @  20  cents .     .-  i.oo 

Apples,  40  Ib.  @  4  cents    ....     ....,.".     .     .  1.60 

Table  showing  the  cost  of  various  foods,  each  of  which  will  contain 
three  ounces  of  protein. 


Corn  meal,  i ^  Ib.  @  3  cents       ....     .     .     .     .     $0.05 

Potatoes,  5  Ib.  @  i  cent        .     .     .     .     n;    .     .     .     .   .    0.05 

Oatmeal,  i£  Ib.  @  5  cents     .     .     .     .K.*..".     .     .     »  0.06 

White  bread,  if  Ib.  @  6  cents o.io 

Beans,  i|  Ib.  @  8  cents     .     .     .     .     .     .     .     .     .     ..  0.12 

Cheese,  i|  Ib.  @  16  cents 0.20 

Beef,  round,  i£  Ib.  @  20  cents 0.30 

Milk,  4  qt.  @  8  cents 0.32 

Apples,  8  Ib.  @  4  cents 0.32 

Eggs,  2  doz.  @  20  cents .  0.40 

Bananas,  2  doz.  @  20  cents 0.40 

Beets,  13  Ib.  @  5  cents 0.65 

Salt  codfish,  6  Ib.  @  15  cents 0.90 

Fresh  codfish,  7  Ib.  @  14  cents 0.98 

Beef,  dried,  2\  Ib.  at  40  cents *     .  i.oo 

Chicken  meat,  5  Ib.  @  30  cents .  1.50 

Oysters,  10  pints  @  20  cents 2.00 

Table  showing  the  cost  of  various  foods,  each  of  which  will  produce 
2400  calories  of  heat. 


240 


FOODSTUFFS 


Food  Groups.  -  -  The  foods  in  grocery  stores  and 
butcher  shops  may  be  divided  into  about  ten  groups. 
These  groups  are  cereals,  beans,  potatoes,  garden 
vegetables,  fruit,  meat,  fish,  shellfish,  eggs,  and  milk. 

Cereals.  -  -  The  different  kinds  of  grain  are  called 
cereals.  There  are  not  great  differences  in  the  com- 
position and  digestibility  of 
the  different  kinds  of  grain, 
or  in  the  flour  which  is  made 
from  them.  All  the  cereals 
contain  protein,  and  a  great 
deal  of  starch.  The  only  ce- 
reals which  contain  much  fat 
are  oats  and  corn. 

Bread,  oatmeal,  and  other 
foods  made  from  grain  are  the 
most  useful  and  important  of 
all  foods.  A  person  can  live 
on  them  alone  if  he  chooses, 
for  they  form  a  fairly  well-balanced  diet  (p.  218).  Mil- 
lions of  people  live  almost  wholly  on  rice. 

Cereals  are  the  cheapest  of  all  foods.  About  five  cents' 
worth  of  corn  meal  will  supply  all  the  food  material 
that  a  man  needs  in  a  day. 

Value  of  White  Flour.  —  White  flour  is  made  by 
sifting  the  indigestible  skins  and  coarse  particles  from 
the  finer  parts.  Bread  made  from  the  best  white  flour 
is  as  nutritious  as  bread  made  from  whole  wheat,  and 
it  may  be  digested  with  greater  ease. 


m 

Grains  of  cornstarch. 


FOODSTUFFS  241 

Bread.  —  Bread,  biscuit,  crackers,  and  plain  cake 
are  nearly  alike  in  composition  and  digestibility.  All 
these  foods  are  full  of  bubbles,  and  are  said  to  be  light. 
The  bubbles  are  made  by  carbon  dioxide  which  is  formed 
when  yeast  or  baking  powder  is  added  to  wet  flour 
(p.  48) .  When  the  wet  flour  is  baked,  it  hardens  in  the 
form  of  thin- walled  bubbles,  which  may  easily  be  chewed. 
Wheat  flour  may  readily  be  made  into  light  bread,  for 
its  protein  becomes  sticky  when  it  is  wet.  The  protein 
of  corn  meal  does  not  become  sticky,  and  so  corn  meal 
cannot  be  made  into  light  bread  unless  it  is  mixed 
with  wheat  flour  or  eggs. 

Beans  and  Peas.  —  Dried  beans  and  peas  are  rich 
in  protein  and  starch,  but  they  contain  very  little  fat. 
If  they  are  cooked  with  fat  pork,  they  become  a  well- 
balanced  diet.  They  are  not  suited  to  persons  who 
have  weak  stomachs,  but  they  are  excellent  for  hardy 
men  who  work  out  of  doors,  for  in  such  persons  the 
stomach  usually  grows  strong  with  the  muscles.  They 
cost  about  eight  cents  a  pound,  and  the  protein  and 
starch  in  them  are  nearly  as  cheap  as  in  cereals. 

Peanuts  are  a  kind  of  pea  whose  pods  are  hard,  like 
thin  nutshells.  They  are  like  peas  in  composition, 
except  that  they  have  fat  in  the  place  of  about  half 
of  the  starch  of  peas.  They  cannot  be  digested  easily, 
and  if  they  are  eaten  between  meals,  they  are  as  harm- 
ful as  beans  would  be. 

Most  nuts  are  like  peanuts  in  composition,  digesti- 
bility, and  food  value. 

GEN.   HYG. l6 


242 


FOODSTUFFS 


Potatoes.  —  Potatoes  are  about  four  fifths  water, 
one  sixtieth  protein,  and  one  seventh  starch.  They 

contain  almost  no 
fat  at  all,  but  if 
they  are  cooked 
with  meat,  as  in 
a  stew,  the  mix- 
ture becomes  a 
well-balance  d 
diet.  When  po- 
tatoes are  dried, 
they  have  about 
the  same  food 
value  as  the  least 
nourishing  of  the 
grains.  They  can- 
not be  digested  so  easily  as  cereals  unless  they  are 
cooked  for  a  long  time. 

The  cost  of  potatoes  varies  greatly  in  different  sea- 
sons of  the  year.  When  they  may  be  bought  for 
fifty  cents  per  bushel,  they  are  almost  as  cheap  a  food 
as  cereals. 

Garden  Vegetables.  —  Garden  vegetables,  such  as 
beets,  onions,  cabbage,  and  celery,  are  mostly  water, 
and  contain  very  little  protein,  starch,  or  sugar,  and 
almost  no  fat.  They  have  very  little  flesh-forming  or 
fuel  value.  Yet  if  a  person  does  not  eat  them  at  all,  he 
becomes  weak  and  sick,  for  they  contain  small  amounts 
of  iron  and  other  substances  which  the  body  needs. 


Starch  grains  in  a  thin  slice  of  potato. 


FOODSTUFFS  243 

Crews  of  ships  on  long  voyages  used  to  suffer  with 
a  disease,  called  scurvy,  in  which  the  mouth  and  skin 
became  tender ^and  sore.  The  disease  was  caused  prin- 
cipally by  a  lack  of  fresh  vegetables,  but  now  the  disease 
is  very  rare,  for  fresh  vegetables  and  fruit  are  carried 
in  a  canned  or  preserved  form.  Only  a  small  quantity 
of  vegetables  is  needed  in  order  to  prevent  scurvy. 

Most  kinds  of  garden  vegetables  cannot  be  digested 
easily.  By  using  them  as  side  dishes,  or  as  flavoring 
for  other  food,  a  person  will  take  as  much  of  them  as 
his  body  needs.  Protein  and  starch,  in  the  form  of 
turnips,  cabbage,  and  green  corn,  cost  about  ten  times 
as  much  as  they  do  in  the  form  of  cereals. 

Fruit.  —  Dates,  bananas,  and  grapes,  each  contain 
a  considerable  amount  of  protein,  and  a  large  amount 
of  sugar.  Almost  the  only  food  substance  in  berries, 
apples,  oranges,  peaches,  and  most  other  juicy  fruits  is 
sugar.  The  skin  and  seeds  of  fruits  cannot  be  digested 
at  all,  and  the  soft  pulp  cannot  be  digested  so  easily 
as  cereal  food.  Most  fruits  have  about  the  same  food 
value  as  garden  vegetables,  and  they  can  take  the  place 
of  vegetables  in  a  diet.  They  are  more  expensive  than 
vegetables,  and  are  far  more  expensive  than  cereals. 
Dried  fruits  contain  all  the  food  substances  that  are 
found  in  fresh  fruits,  and  are  far  cheaper  than  the  fresh 
fruits. 

Meat.  — The  flesh  of  animals  is  called  meat,  but  by 
the  word  meat  we  usually  mean  the  flesh  of  beef  cattle, 
pigs,  sheep,  and  chickens.  Meat  is  about  one  sixth 


244  FOODSTUFFS 

protein.  Some  kinds  of  meat  contain  a  great  deal  of 
fat,  and  other  kinds  have  very  little  fat,  but  no  meat 
contains  sugar  or  starch.  The  different  kinds  of  meat, 
such  as  beef,  pork,  and  chicken,  do  not  differ  greatly 
in  composition,  or  ease  of  digestion,  but  there  are  great 
differences  in  their  cost. 

Some  persons  suppose  that  the  expensive  kinds  of 
beef,  such  as  sirloin  steak,  are  more  nourishing,  and 
may  be  digested  more  easily,  than  the  cheapest  kinds, 
such  as  meat  from  the  neck  of  an  animal.  This  is  not 
so.  There  is  very  little  difference  in  the  food  values 
of  the  various  kinds  of  beef.  The  principal  difference 
is  in  the  toughness  and  taste  of  the  meat,  but  a  good 
cook  can  make  tough  meat  as  tender  and  as  tasty  as 
the  dearer  kinds  of  meat. 

Meat  foods  cost  several  times  as  much  as  cereal 
foods,  but  meat  may  usually  be  digested  more  easily 
than  cereal  food.  A  person  can  live  a  healthy  life  with- 
out meat ;  but  a  mixture  of  meat  with  cereals,  potatoes, 
beans,  and  other  vegetable  foods  is  usually  more  whole- 
some, and  forms  a  more  balanced  diet  than  either 
vegetable  food,  or  meat  food  alone  would  do. 

Some  persons  suppose  that  a  teaspoonful  of  beef 
tea,  or  of  meat  juice,  or  of  meat  extract,  contains  as 
much  nourishment  as  a  pound  of  beef.  These  liquid 
foods  contain  almost  no  nourishment  at  all,  for  the 
substances  which  have  a  food  value  cannot  be  dissolved 
from  the  meat.  The  principal  value  of  meat  teas  and 
meat  extracts  is  their  taste  (p.  212). 


FOODSTUFFS  245 

Fish.  --  The  meat  of  fish  is  almost  like  the  meat  of 
cattle  in  composition  and  food  value,  except  that  it 
usually  contains  more  water,  and  is  less  easy  to  digest. 
It  differs  from  beef  principally  in  its  taste.  If  fish 
is  well  cooked,  it  may  take  the  place  of  meat.  Protein 
in  the  cheaper  kinds  of  fish  is  almost  as  cheap  as  it  is 
in  cereals.  Dried  codfish  is  one  of  the  cheapest  of  all 
the  flesh-forming  foods. 

Shellfish.  —  Oysters,  clams,  lobsters,  crabs,  and  other 
shellfish  are  like  fish  and  meat,  except  that  they  usually 
contain  a  little  sugar,  and  a  great  deal  of  water.  The 
food  substances  in  them  are  about  three  times  more 
expensive  than  in  meat. 

Shellfish  are  usually  taken  from  the  bottom  of  bays 
and  creeks.  If  sewage  empties  into  the  water  near 
them,  they  are  likely  to  carry  disease  germs  on  their 
shells  and  in  their  digestive  tubes.  But  if  the  shell- 
fish are  cooked,  the  disease  germs  in  them  will  be 
killed. 

Eggs.  —  Eggs  have  about  the  same  composition  and 
food  value  as  meat.  They  may  usually  be  digested 
readily,  whether  they  are  raw  or  are  cooked  in  any 
good  way.  Their  ease  of  digestion  depends  principally 
on  the  size  of  the  lumps  which  are  swallowed.  A  raw 
egg  may  form  a  large  mass  which  the  digestive  juices 
cannot  readily  enter.  A  hard-boiled  egg  may  be  quickly 
digested  if  it  is  chewed  to  small  bits. 

A  dozen  eggs  weigh  about  a  pound  and  a  half.  At 
twenty-four  cents  a  dozen  they  have  about  the  same 


246  FOODSTUFFS 

food  value  as  a  cheap  form  of  meat,  but  at  forty  cents 
a  dozen  they  are  an  expensive  food. 

Milk.  —  Cow's  milk  is  a  complete  and  well-balanced 
food,  for  it  contains  protein,  fat,  sugar,  minerals,  and 
water  in  nearly  the  quantities  that  the  body  needs.  One 
eighth  of  it  is  solid  substance,  and  a  cup  of  it  contains 
more  solid  food  than  a  cup  of  oysters.  A  person  doing 
light  work  would  need  no  more  food  than  four  quarts 
of  milk  a  day.  It  contains  rather  more  protein  than 
a  grown  person  needs,  but  it  is  the  best  of  all  foods  for 
young  children,  for  they  need  a  great  deal  of  protein 
in  forming  new  flesh  while  they  grow  in  size.  Milk  at 
eight  cents  a  quart  is  as  cheap  a  food  as  cheap  meat. 

Milk  may  be  digested  readily,  and  it  contains  almost 
no  indigestible  substances  at  all.  It  is  one  of  the  most 
valuable  of  all  foods  for  persons  who  are  sick  or  have 
weak  stomachs. 

Some  persons  often  drink  milk  instead  of  water  when 
they  are  thirsty,  and  are  not  in  need  of  food.  Milk  is 
a  food  as  well  as  a  drink.  Taking  it  between  meals 
or  after  a  meal  is  as  harmful  as  taking  any  other  food 
when  the  body  has  no  need  of  it. 

Foods  made  from  Milk.  -  -  The  fat  of  milk  is  in  tiny 
drops  which  float  through  its  liquid  and  make  it  appear 
white.  When  the  milk  stands  quietly  for  a  few  hours, 
the  fat  rises  to  the  surface  and  forms  a  layer  called 
cream.  After  the  cream  has  been  removed,  the  milk 
that  is  left  is  called  skim  milk. 

Milk  which  contains  a  great  deal  of  cream  is  called 


FOODSTUFFS 


247 


1) 

8 


rich  milk ;  if  it  contains  a  small  quantity  of  cream  it  is 

called  thin  milk.     Many  persons  suppose  that   thin 

milk  and  skim-milk  are  of 

little  value  as  food.    Thin 

milk  and  skim  milk  each 

contains  about  as  much 

protein  and  sugar  as  rich 

milk.     Taking  the  cream 

from  milk  does  not  spoil 

it  for  food,  for  nearly  all 

the  protein  and  sugar  are 

left    in    the    skim    milk. 

The  price  of  skim  milk 

Fat  drops  in  cream.    Magnified. 

is  only  about  half  that 

of  whole  milk,  but  it  has  much  more  than  half  the  food 

value  of  whole  milk. 

Cream  is  about  one  fifth  fat,  and  contains  about  as 
much  protein  and  sugar  as  milk  itself.  When  it  is 
shaken  or  stirred,  its  fat  collects  into  a  solid  lump  called 
butter.  The  liquid  that  is  left  is  called  buttermilk,  and 
has  about  the  same  food  value  as  skim  milk. 

Cheese.  --The  protein  of  milk  becomes  solid  when 
the  milk  is  mixed  with  a  substance,  called  rennet,  which 
contains  the  digestive  juice  of  a  calf's  stomach.  When 
the  solid  protein  is  pressed  into  a  mass  it  is  called 
cheese.  Most  cheese  also  contains  a  large  quantity 
of  fat.  The  flavor  of  cheese  is  caused  by  bacteria 
which  grow  either  in  the  milk,  or  in  the  cheese  after 
it  has  stood  for  a  few  days  or  weeks.  Cheese  is  one  of 


248  FOODSTUFFS 

the  most  nourishing  of  all  foods,  and  it  may  usually 
be  digested  easily.  At  fifteen  cents  a  pound  it  is  as 
cheap  a  food  as  cheap  meat. 

Tea  and  Coffee.  —  Tea  and  coffee  are  two  drinks 
which  most  persons  have  on  their  tables.  Tea  is  made 
from  the  dried  leaves  of  the  tea  tree,  and  coffee  is  made 
from  the  roasted  berries  of  the  coffee  tree.  They  each 
contain  a  substance,  called  caffeine,  which  keeps  a  per- 
son awake,  and  rouses  his  mind  to  work.  Tea  and 
coffee  are  stimulants,  and  do  not  supply  the  body  with 
any  food  substance.  The  drinks  are  of  value  to  grown 
persons  who  have  to  do  hard  work.  They  also  have 
a  great  value  in  some  forms  of  sickness,  but  they  do 
more  harm  than  good  to  children.  If  you  cannot  work 
or  keep  awake  without  them,  there  is  something  the 
matter  with  you,  and  neither  of  the  drinks  will  be  of 
any  real  help  to  you. 

Cocoa.  —  Cocoa  and  chocolate  are  drinks  which  are 
made  from  the  roasted  seeds  of  the  cacao  tree.  They 
each  contain  a  substance  which  is  like  caffeine,  only 
it  is  somewhat  weaker.  For  this  reason  children  can 
usually  drink  cocoa  and  chocolate  more  safely  than  tea 
or  coffee. 

QUESTIONS 

What  is  the  cost  of  a  pound  of  sugar?  of  starch?  of  fat? 
of  protein  ? 

Name  the  principal  food  groups. 
What  are  cereals? 


FOODSTUFFS  249 

What  food  elements  do  cereal  foods  contain  ? 

What  is  light  bread  ? 

Why  cannot  corn  meal  alone  be  made  into  light  bread  ? 

If  a  man  should  live  on  corn  meal  alone,  how  much  would  a 
day's  supply  of  food  cost  ? 

What  food  substances  do  dried  beans  and  peas  contain  ? 

How  much  would  a  diet  of  dried  beans  cost  a  man  daily  ? 

For  what  class  of  persons  are  dried  beans  well  suited  ? 

What  is  the  food  value  of  peanuts  ? 

What  food  substances  are  contained  in  potatoes  ? 

How  much  would  a  diet  of  potatoes  cost  a  man  daily  ? 

Why  does  a  person  need  to  eat  garden  vegetables  ? 

How  may  scurvy  be  prevented  ? 

What  is  the  food  value  of  fruit  ? 

How  do  dried  fruits  compare  with  the  fresh  fruits  in  food 
value  ? 

What  food  substances  are  found  in  meat  ? 

How  does  meat  differ  from  cereals  in  composition  ?  in  diges- 
tibility ?  in  cost  ? 

What  is  the  principal  difference  between  the  expensive  kinds 
of  meat,  and  the  cheaper  kinds  ? 

What  food  value  has  beef  tea  ? 

How  do  fish  compare  with  meat  in  food  value  ? 

What  is  the  difference  in  food  value  between  shellfish  and 
meat? 

What  food  substances  are  found  in  eggs  ? 

On  what  does  the  digestibility  of  eggs  depend  ? 

At  what  price  per  dozen  would  eggs  be  a  cheap  food  ? 

What  food  substances  are  found  in  milk  ? 

Why  is  milk  one  of  the  most  valuable  of  all  foods  for 
children  ? 

How  much  milk  would  a  man  doing  hard  work  need  to  drink 
if  he  took  no  other  food  ? 

What  is  the  objection  to  the  use  of  milk  to  quench  thirst  ? 


250  FOODSTUFFS 

What  is   the  food   value   of   cream?    of   skim    milk?     of 
buttermilk  ?    of  butter  ? 

Of  what  food  elements  does  cheese  consist  ? 

Why  are  coffee  and  tea  called  stimulants,  and  not  foods  ? 

What  substance  in  tea  and  coffee  is  a  stimulant  ? 

Why  is  cocoa  a  better  drink  for  children  than  tea  and  coffee  ? 


CHAPTER  XXIV 
WHOLESOME  FOOD 

Storing  Food.  —  Fruit,  meat,  and  many  other  foods 
which  naturally  decay  within  a  few  days  may  be  pre- 
served for  a  long  time  if  proper  care  is  taken  to  prevent 
bacteria  and  molds  from  growing  in  them.  Three 
ways  of  preserving  foods  in  large  quantities  are  by 
canning  them,  by  drying  them,  and  by  putting  them 
in  cold  storage. 

Canned  Foods.  —  Cooked  foods  will  remain  fresh 
for  years  if  they  are  properly  canned,  for  they  are  then 
protected  from  bacteria  and  molds  (p.  39).  Sub- 
stances such  as  benzoate  of  soda  are  sometimes  added 
to  canned  goods  to  keep  them  from  spoiling.  Coloring 
matter  is  sometimes  added  to  preserve  their  appearance. 
If  food  is  fresh,  and  is  properly  canned,  it  will  retain 
its  appearance  and  wholesomeness  for  years  without 
the  addition  of  preservatives. 

Drying  Food.  —  Fruits,  vegetables,  and  meat  will 
remain  free  from  bacteria  and  molds,  and  will  keep 
fresh,  if  they  are  dried  and  are  then  stored  in  a  dry 
place.  Food  that  has  been  properly  dried  and  stored 
has  the  same  food  value  that  it  had  while  it  was  fresh. 
Dried  apples  are  cheap,  and  may  be  bought  at  any  sea- 

251 


252  WHOLESOME   FOOD 

son  of  the  year,  and  when  cooked  they  have  the  same 
food  value  that  they  would  have  had  if  they  had  been 
cooked  while  they  were  fresh.  The  principal  reason 
why  dried  fruit  often  has  less  food  value  than  fresh 
fruit  is  that  the  best  fruit  is  usually  sold  fresh,  and  the 
poorer  fruit  is  dried. 

Cold  Storage.  —  Large  quantities  of  meat,  fish,  eggs, 
and  other  food  are  preserved  fresh  for  many  months  by 
storing  them  in  rooms  which  are  kept  at  about  a  freez- 
ing temperature.  The  cold  prevents  the  growth  of 
bacteria  and  molds,  and  also  prevents  other  changes 
which  would  naturally  take  place  in  the  food.  The 
principal  objects  of  cold  storage  are  to  preserve  a  food 
while  it  is  taken  long  distances  to  market,  and  to  store  it 
safely  while  it  is  abundant  in  order  that  it  may  be  used 
when  a  new  supply  of  the  food  cannot  be  obtained. 
The  meat  and  fish  which  are  used  in  large  cities  usually 
come  to  market  in  cold  storage  cars,  and  are  kept  in 
cold  storage  until  they  are  used.  It  would  be  almost 
impossible  to  supply  a  large  city  with  food  without 
cold  storage. 

All  kinds  of  food  that  are  not  injured  by  the  cold 
may  be  preserved  in  cold  storage.  If  a  food  is  poor  in 
quality,  or  is  spoiled  when  it  is  placed  in  cold  storage, 
it  will  be  in  the  same,  or  a  worse,  state  when  it  is  taken 
out.  If  it  is  fresh  and  wholesome  when  it  is  placed  in 
cold  storage,  it  will  remain  wholesome  for  months. 

Keeping  Food  Fresh.  —  Many  kinds  of  food,  such 
as  meat,  milk,  and  cooked  foods,  usually  turn  sour,  or 


WHOLESOME   FOOD  253 

spoil,  within  a  very  few  days  after  they  are  brought  into 
the  kitchen,  or  prepared  for  the  table,  unless  great 
pains  are  taken  to  keep  them  fresh.  Food  will  not 
decay  or  turn  sour  if  no  bacteria  or  molds  grow  in  it 
(p.  39).  There  are  three  principal  ways  of  keeping 
food  from  spoiling  in  a  kitchen  or  pantry. 

1.  Food  will  not  decay  if  it  is  kept  dry,  for  bacteria 
will  not  grow  without  water.     For  this  reason  dry 
crackers  will  keep  longer  than  bread,  and  dried  beef 
will  keep  longer  than  fresh  meat.     Storing  food  in  a 
dry  place  is  a  great  help  in  keeping  it  fresh. 

2.  Food  will  not  spoil  if  it  is  kept  cold,  for  bacteria 
grow  very  slowly  in  cold  places.     Frozen  meat  will  not 
spoil  at  all,  but  freezing  will  injure  most  vegetables  and 
fruit.     A  cold  cellar  or  an  ice  box  is  a  great  help  in 
keeping  food  fresh. 

3.  If  food  is  clean,  it  will  have  very  few  bacteria  in 
it,  and  will  keep  fresh  for  a  long  time.     Clean  hands, 
clean  dishes,  a  clean  pantry,  and  keeping  flies  away 
from  food,  are  all  great  helps  hi  keeping  food  from 
spoiling. 

Sour  Milk.  —  Milk  spoils  and  turns  sour  more  readily 
than  most  other  common  foods.  The  souring  is  caused 
by  bacteria  which  fall  into  the  milk  with  dust  and  dirt. 
Some  kinds  of  bacteria  growing  in  milk  produce  a 
sour  substance  called  lactic  acid,  which  curdles  the 
protein  of  the  milk  and  makes  it  like  jelly.  The  bac- 
teria which  turn  milk  sour  are  not  usually  harmful  to 
grown  persons,  and  do  not  spoil  the  milk  for  cooking. 


254 


WHOLESOME   FOOD 


But  any  milk  that  is  about  to  turn  sour,  or  that  contains 
many  bacteria,  is  dangerous  for  children  and  babies, 
for  it  usually  contains  bacteria  which  produce  sickness. 

Disease  Germs  in  Milk.  —  Milk  which  contains 
harmful  bacteria  is  the  cause  of  over  a  quarter  of  all 
deaths  among  babies.  Nearly  all  intestinal  diseases 
among  young  children  are  due  to  unclean  milk.  Babies 
are  more  likely  to  have  these  diseases  in  summer  than 
in  winter,  because  most  milk  spoils  quickly  during 
warm  weather,  unless  it  is  kept  cool. 

Any  form  of  dirt  in  milk  may  contain  disease  germs. 
Scarlet  fever,  or  diphtheria,  or  typhoid  fever,  may  be 
spread  along  a  whole  milk  route  by  means  of  milk 
which  has  come  from  a  house  in  which  some  one  is 
sick  with  the  disease. 


Milk  from  an  unclean  cow  is  not  wholesome 


WHOLESOME   FOOD 


255 


A  clean  cow. 


Wholesome   Milk.  —  Wholesome  milk  means  milk 

which  is  clean  and  almost  free  from  bacteria.     The  dirt 

comes  from  dirty  cows,  dirty  stables,  and  the  dirty 

clothes    and   hands  of 

the    milkmen.      Many 

farmers     laugh     when 

they  are  told  about  the 

good  which  would  come 

from    sweeping   and 

scrubbing    the    cow 

stables,    currying    and 

brushing    the    cows, 

washing  the  hands  and 

putting  on  clean  clothes  before  milking,  and  carrying 

the  milk  at  once  to  clean  rooms.     But  these  things 

must  be  done  if 
milk  is  to  be  whole- 
some.  What  is 
called  certified  milk 
in  New  York  is 
pure  because  it  is 
produced  in  this 
cleanly  way.  It  is 
almost  the  only 
milk  which  may  be 

safely  fed  to  babies  without  first  doing  something  to  it 

to  kill  the  germs  (see  frontispiece). 

Some  persons  suppose  that  the.  harmful  dirt  may  be 

strained  from  milk.     This  is  not  so.     Thousands  of 


A  manure  pile  near  a  dairy  is  dangerous. 


256  WHOLESOME   FOOD 

bacteria  will  be  washed  off  from  every  speck  of  dirt  as 
large  as  a  grain  of  sand,  and  there  is  no  way  of  remov- 
ing them  from  the  milk.  If  there  is  any  dirt  at  all  in 
the  bottom  of  a  milk  pail  or  pitcher,  or  on  the  strainer, 
that  milk  is  sure  to  be  loaded  with  bacteria.  It  will 
not  keep  well,  and  will  not  be  fit  to  be  fed  to  small 
children,  unless  the  bacteria  in  it  are  killed. 

Dirt  often  falls  into  milk  while  it  is  being  handled 
in  open  cans.  The  cleanest  way  of  carrying  milk  to 
market  is  to  place  it  in  clean  bottles  as  soon  as  it  is 
milked,  and  then  to  seal  the  bottles,  so  that  no  dirt 
can  get  into  them. 

Buy  your  milk  from  a  man  who  has  clean  stables, 
clean  cows,  clean  milk  cans,  clean  hands,  and  clean 
clothes.  Put  it  in  a  clean  pail  or  pitcher,  and  keep  it 
in  a  clean  place,  and  away  from  flies.  Choose  bottled 
milk,  if  possible. 

Cooling  Milk.  —  The  number  of  bacteria  in  each 
drop  of  ordinary  milk  is  several  thousand  while  it  is 
fresh,  and  is  often  many  million  after  it  has  stood  for 
a  few  hours  in  a  warm  room.  The  cleanest  milk  that 
may  be  bought  or  produced  will  have  a  few  hundred 
bacteria  in  each  drop.  These  will  not  usually  do  harm 
if  they  do  not  increase  in  number. 

The  easiest  way  to  keep  bacteria  from  growing  is 
to  cool  the  milk,  for  they  will  hardly  grow  at  all  if  the 
milk  is  kept  as  cold  as  water  in  an  ordinary  well  or 
pump.  Those  who  produce  wholesome  milk  cool  it 
as  soon  as  it  is  milked,  and  keep  it  cool  until  it  is  sold. 


WHOLESOME   FOOD  257 

Buy  milk  which  was  cooled  as  soon  as  it  was  milked,  and 
was  kept  cool  until  it  was  sold.  Keep  it  in  a  cellar, 
or  ice  box,  or  other  cool  place. 

Pasteurizing  Milk.  —  Heating  milk  boiling  hot  will 
kill  all  the  germs  that  may  be  in  it.  This  is  called 
sterilizing  it.  But  a  boiling  heat  changes  its  taste, 
and  makes  it  less  digestible  than  raw  milk. 

Heating  milk  to  a  temperature  a  little  below  boiling 
will  kill  nearly  all  the  bacteria  which  may  be  in  it. 
This  is  called  Pasteurizing  it.  The  heat  does  not  change 
the  taste  or  the  digestibility  of  the  milk.  Pasteurized 
milk  is  a  safe  food  for  babies,  if  the  milk  is  fresh  when  it 
is  heated,  and  is  afterwards  kept  cool  and  clean. 

Food  sold  on  the  Streets.  —  Food  which  is  sold  from 
carts,  or  is  placed  in  front  of  stores  for  show,  often  be- 
comes soiled  with  dust  and  dirt  from  the  street,  and  by 
flies  which  light  upon  it,  and  by  the  dirty  hands  of 
those  who  handle  it.  In  all  of  these  ways  disease 
germs  are  often  left  upon  food  which  is  kept  in  front 
of  stores.  Do  not  buy  food  from  these  places,  unless 
you  afterwards  cook  it  so  as  to  kill  all  the  disease  germs 
which  may  be  on  it. 

Adulterated  Food.  —  Some  foods  which  appear  to 
be  pure  contain  substances  which  are  added  to  make 
poor  goods  appear  to  be  of  good  quality.  These 
foods  are  called  adulterated.  Milk  is  sometimes 
adulterated  with  water,  coffee  with  chicory  root,  and 
olive  oil  with  cottonseed  oil.  Benzoate  of  soda  is 
often  added  to  catchup  in  order  to  preserve  it. 

GEN.   HYG. 17 


258 


WHOLESOME   FOOD 


A  great  many  medicines  which  are  advertised  as 
harmless  contain  harmful  drugs.  Nearly  all  pain 
killers  and  soothing  sirups  contain  opium,  most  tonics 
contain  as  much  alcohol  as  strong  wine,  and  most 
headache  cures  contain  substances,  such  as  phenacetin, 
which  produce  dangerous  weakness  of  the  heart. 

Pure  Food  Laws.  —  Deceiving  people  by  selling 
adulterated  foods  and  harmful  drugs  is  a  crime.  Many 
countries  and  states  have  laws  that  all  packages  of 
foods  and  drugs  that  are  sold  shall  be  marked  with  a 
list  of  the  substances  which  they  contain.  The  object 
of  the  laws  is  to  enable  those  who  buy  goods  to  know 
what  kind  of  articles  they  are  buying. 

Cooking.  -  -  The 
juices  of  the  diges- 
tive organs  cannot 
digest  some  kinds 
of  foods  readily  un- 
less the  foods  are 
cooked.  Starch 
forms  the  principal 
part  of  grain  and 
vegetables.  The 
starch  in  each 
starch  grain  is  in 
layers  which  are 
separated  by  thin 
sheets  of  an  indi- 


Grains  of  potato  starch.     Magnified. 


gestible  substance  like  paper.     When  food  is  cooked, 


WHOLESOME   FOOD  259 

the  heat  makes  the  layers  of  starch  swell,  and  causes 
the  grains  to  burst  open.  The  digestive  juices  can 
then  reach  the -starch  and  easily  digest  it. 

Much  of  the  protein  of  meat  and  vegetables  is  in  a 
tough,  hard  form  which  cannot  be  easily  dissolved  by 
the  digestive  juices.  Cooking  softens  the  protein,  and 
makes  the  food  so  soft  and  tender  that  the  digestive 
juices  easily  soak  into  it. 

The  fat  in  nearly  all  kinds  of  food  is  held  in  tiny 
pockets  of  protein  (p.  30).  Cooking  softens  the 
pockets,  and  sets  the  fat  free. 

Long  Cooking.  —  Most  kinds  of  food  may  be  digested 
more  readily  when  they  are  cooked  than  when  they 
are  raw.  Very  few  kinds  are  made  less  digestible  by 
long  cooking.  Most  foods  made  from  grain  cannot 
be  digested  readily  unless  they  have  been  cooked  for 
at  least  an  hour  or  two.  Oatmeal  may  be  soft  and 
may  taste  good  after  it  has  been  cooked  for  only  fifteen 
minutes,  but  it  will  not  be  readily  digested  unless  it 
has  been  cooked  for  some  hours.  A  good  way  of  pre- 
paring it  for  breakfast  is  to  put  it  on  to  boil  in  the 
evening,  and  let  it  cook  slowly  all  night. 

Pancakes  are  usually  hard  to  digest  because  they 
are  cooked  for  only  a  short  time.  If  they  are  cooked 
for  ten  or  fifteen  minutes,  or  if  they  are  made  from  meal 
which  has  been  cooked,  they  may  be  digested  as  easily 
as  bread.  Baked  potatoes  may  usually  be  digested 
readily,  because  they  are  cooked  for  a  long  time  and 
at  a  high  temperature. 


260  WHOLESOME   FOOD 

Stews.  -  -  When  meat  is  cooked,  some  of  its  juices 
and  fat  run  out.  If  the  liquid  is  thrown  away,  much  of 
the  nourishment  and  a  great  deal  of  the  best  tasting 
parts  of  the  meat  are  wasted.  A  good  way  of  cooking 
meat  is  to  make  it  into  a  stew  or  thick  soup  with  pota- 
toes and  vegetables.  This  method  saves  all  the  nourish- 
ment that  is  in  the  raw  food. 

Another  good  way  to  cook  meat  is  to  place  it  in  a 
hot  oven  for  a  few  moments  so  that  a  crust  will  form 
over  it  quickly  and  prevent  the  juices  from  escaping. 
Then  allow  the  oven  to  cool  a  little,  so  that  the  meat  will 
cook  slowly  without  burning. 

Desserts.  —  Pie,  cake,  and  pudding  are  cooked 
mixtures  of  flour,  sugar,  fat,  eggs,  and  fruit,  and  are 
usually  hard  to  digest.  A  person  would  soon  get  tired  of 
them  if  he  had  to  live  on  them  alone.  Their  food  value 
is  that  of  the  flour,  eggs,  and  other  things  of  which  they 
are  made. 

Cooking  and  Disease  Germs.  —  Food  may  contain 
disease  germs  which  have  come  from  dust  or  dirt,  or 
from  the  milk  or  meat  of  diseased  animals,  or  from 
house  flies,  or  from  other  sources.  If  food  is  well  cooked, 
the  heat  will  kill  all  the  disease  germs  that  are  in  the 
food. 

Food  for  the  Sick.  —  Sick  persons  cannot  digest 
food  well.  They  need  food  which  may  be  easily 
digested,  and  which  contains  very  little  indigestible 
substance.  For  this  reason  eggs,  milk,  and  toast  are 
usually  the  best  kinds  of  food  to  use  during  sickness. 


WHOLESOME   FOOD  261 

Learn  to  like  these  simple  kinds  of  food  so  that,  if  you 
should  be  sick,  you  will  be  able  to  take  the  foods  which 
are  the  best  foe  you. 

QUESTIONS 

What  is  the  cause  of  the  spoiling  of  food  ? 

How  does  dryness  help  to  preserve  food  from  spoiling  ? 

How  does  a  low  temperature  help  to  preserve  food  from 
spoiling  ? 

How  does  cleanliness  help  to  preserve  food  from  spoiling  ? 

Why  do  foods  remain  fresh  when  they  are  properly  canned  ? 

How  does  drying  affect  the  food  value  of  fruit  and  vegetables  ? 

When  food  is  properly  kept  in  cold  storage  rooms,  how  is 
its  food  value  affected  ? 

Name  three  ways  in  which  .food  may  be  kept  fresh  in  a 
kitchen  or  pantry. 

What  is  the  cause  of  the  souring  of  milk  ? 

What  is  meant  by  wholesome  milk  ? 

Where  do  the  bacteria  that  are  in  milk  come  from  ? 

How  may  milk  be  produced  almost  free  from  bacteria  ? 

Why  is  bottled  milk  usually  more  wholesome  than  milk 
sold  from  large  cans  ? 

Why  is  cold  milk  more  likely  to  remain  wholesome  than  warm 
milk? 

How  is  milk  Pasteurized? 

Why  is  Pasteurized  milk  usually  more  wholesome  for  babies 
than  raw  milk? 

Why  is  food  that  is  sold  from  stands  on  the  streets  likely  to 
be  unwholesome  ? 

What  is  an  adulterated  food  ? 

What  is  the  object  of  pure  food  laws  ? 

What  effect  does  cooking  have  on  starch  ? 


262  WHOLESOME   FOOD 

What  effect  does  cooking  have  on  protein  ? 

What  effect  does  cooking  have  on  fat  ? 

What  effect  has  long  cooking  on  the  digestibility  of  vegetable 
foods  ? 

Why  is  a  stew  one  of  the  most  nourishing  forms  of  cooked 
meat? 

What  effect  does  cooking  have  on  disease  germs  that  are  in 
food? 


CHAPTER  XXV 


CARE  OF  THE  NOSE  AND   MOUTH 

Bacteria  in  the  Mouth.  -  -  The  nose  and  the  mouth 
are  the  gateways  through  which  disease  germs  usually 
enter  the  body  (p.  42).  The 
care  of  the  nose  and  mouth  is 
of  great  importance  in  keeping 
the  whole  body  well. 

The  mouth  is  warm  and 
moist,  and  contains  many  sub- 
stajices  on  which  bacteria  may 
live.  Many  kinds  of  bacteria 
are  always  growing  on  the 
tongue  and  cheeks,  and  be- 
tween the  teeth.  The  bacteria 
often  produce  decay  and  bad 
odors.  Disease  germs  also 
enter  the  mouth  and  grow 
there.  Cleansing  the  mouth  is  very  necessary  for 
health. 

Bacteria  in  the  Nose.  —  Bacteria  may  always  be 
found  growing  in  the  nose,  but  if  the  air  passages 
are  large  and  open,  the  mucus  washes  most  of  them 
away  and  prevents  them  from  becoming  great  in  num- 

263 


Bacteria  and  an  epithelial  cell 
from  the  mouth. 


264  CARE   OF   THE   NOSE   AND    MOUTH 

her.  If  the  air  passages  are  stopped  up,  or  if  mucus 
is  allowed  to  collect  in  them,  large  numbers  of  bacteria 
grow  in  the  nose,  just  as  they  do  in  the  mouth. 

Most  house  dust  that  is  breathed  contains  disease 
germs  (p.  139).  If  the  germs  are  allowed  to  lie  in  the 
nose,  they  may  grow  and  produce  colds  and  sore  throats. 
Cleansing  the  nose  is  very  necessary  to  health. 

Bacteria  in  the  Tonsils.  —  If  the  tonsils  are  enlarged, 
they  nearly  always  contain  numbers  of  deep  holes  and 
pockets  (p.  129).  These  holes  become  filled  with 
mucus,  dead  epithelium,  and  bits  of  food.  Bacteria 
lie  in  them  undisturbed,  and  cause  the  contents  of 
the  holes  to  decay.  Disease  germs  also  lodge  in  them 
and  produce  tonsillitis,  sore  throat,  or  other  diseases. 
White  spots  about  the  size  of  pinheads  may  sometimes 
be  seen  on  the  tonsils.  The  spots  are  the  outer  endg  of 
masses  of  decaying  substances  which  fill  the  holes. 
Tonsils  which  are  full  of  holes  are  dangerous  to  health, 
and  should  be  removed  by  a  surgeon. 

Cleansing  the  Nose.  —  Blowing  the  nose  will  usually 
cleanse  it.  The  mucus  in  the  nose  is  a  natural  bath 
which  washes  away  dirt  and  disease'  germs  from  the 
nose.  Blowing  the  nose  is  necessary  for  its  cleanliness, 
and  for  the  health  of  the  whole  body.  A  clean  hand- 
kerchief is  a  very  necessary  thing  for  every  man,  woman, 
and  child  to  carry,  and  to  use. 

Sometimes  the  nose  is  stopped  up  by  a  swelling  of 
its  lining.  Trying  to  blow  the  nose  makes  the  swelling 
worse  and  increases  the  stoppage.  The  swelling  will 


CARE   OF   THE   NOSE   AND   MOUTH  265 

usually  go  down  if  the  breath  is  held  as  long  as  possible 
during  expiration  (p.  128). 

Cleansing  the  Mouth.  —  Washing  the  mouth  with 
water  will  cleanse  it.  Rinsing  your  mouth  with  water 
will  not  wash  away  thick  mucus,  or  the  coating  from 
the  tongue.  Cleanse  your  tongue  and  the  roof  of  your 
mouth  two  or  three  times  a  day  by  rubbing  the  parts 
just  as  you  would  cleanse  the  skin  of  your  face.  Use 
your  fingers,  or  a  swab,  or  a  cloth,  or,  best  of  all,  a 
toothbrush.  By  rubbing  the  mouth  and  tongue  as 
far  back  as  possible  you  will  also  cleanse  the  tonsils, 
and  help  to  empty  their  holes  and  pockets. 

Structure  of  Teeth.  —  A  tooth  is  composed  of  a 
kind  of  hard  bone  called  dentine,  which  is  covered  with 
a  harder  substance  called  enamel.  The  center  of  each 
tooth  has  a  small  hollow  space  containing  nerves  and 
blood  tubes.  The  teeth  are  fixed  in  the  bone  of  the 
jaw  with  a  kind  of  soft  bone  called 
cement. 

Decayed  Teeth.  —  The  teeth  are 
likely  to  decay,  unless  they  receive 
great  care.  The  enamel  of  a  tooth 
will  seldom  decay,  for  it  is  composed 
almost  entirely  of  mineral  sub- 
stances. If  the  enamel  is  injured, 
the  dentine  under  it  readily  decays 
and  becomes  soft.  If  the  decayed 

,  n  ,  A  decayed  tooth  is  the 

part  reaches  the  nerves,  the  tooth      hiding  place  of  dis- 

will  ache.  ease  germs. 


266  CARE   OF   THE  NOSE  AND   MOUTH 

Bacteria  are  the  cause  of  decay  in  teeth,  just  as  they 
are  the  cause  of  decay  in  dead  substances  (p.  37). 
They  cannot  pass  through  sound  enamel,  but  they  may 
enter  the  dentine  through  tiny  cracks,  and  other  in- 
juries in  the  enamel.  The  cracks  may  be  made  by 
biting  upon  hard  substances,  such  as  nutshells.  They 
are  more  often  caused  by  sour  substances  which  dis- 
solve the  minerals  of  the  enamel.  These  harmful 
substances  are  formed  when  food  and  dirt  are  allowed 
to  remain  in  the  mouth.  Keeping  the  teeth  clean  and 
free  from  dirt  helps  to  preserve  them. 

Importance  of  Good  Teeth.  -  -  Teeth  that  are  dirty 
and  decayed  are  unpleasant  to  look  at.  They  are 
signs  of  a  dirty  mouth,  a  bad-smelling  breath,  and  of 
disease  germs  in  the  body.  But  sound,  white  teeth 
are  beautiful  and  pleasing.  They  are  signs  of  clean- 
liness, a  healthy  mouth,  and  of  freedom  from  disease 
germs. 

Brushing  the  Teeth.  —  Cleanse  your  teeth  with  a 
toothbrush  and  water  two  or  three  times  a  day.  Brush 
their  inner  surfaces  as  well  as  their  front  sides,  and  brush 
the  back  teeth  as  well  as  the  front  ones.  Rub  the 
brush  up  and  down  as  well  as  sidewise,  so  that  the 
bristles  will  reach  between  the  teeth.  Also  rub  the 
brush  over  your  tongue  to  cleanse  the  whole  inside  of 
your  mouth.  Brushing  your  teeth  and  cleansing  your 
mouth  will  help  to  keep  your  teeth  from  decaying,  and 
will  also  help  to  prevent  you  from  catching  diseases. 

A  tooth  powder  or  tooth  paste  is  a  useful  article  to 


CARE   OF   THE   NOSE   AND   MOUTH  267 

use  in  brushing  your  teeth.  Many  tooth  powders 
contain  chalk.  This  helps  to  scour  the  teeth  clean,  and 
also  destroys  the  acids  in  the  mouth.  A  soap  that  has 
no  taste  is  also  useful  in  cleansing  the  teeth  and  mouth. 

Particles  of  food  may  become  wedged  between  the 
teeth  so  tightly  that  a  toothbrush  will  not  remove 
them.  Push  them  from  between  the  teeth  with  a  tooth- 
pick made  of  soft  wood.  One  made  of  hard  wood  or 
metal  may  crack  the  enamel  and  start  a  hole  in  the 
tooth. 

You  may  also  remove  food  and  dirt  from  between  the 
teeth  by  passing  a  thread  between  them. 

Decayed  Teeth  and  Disease  Germs.  —  When  a 
tooth  has  a  hole  in  it,  all  kinds  of  bacteria  which  may 
be  in  the  mouth  may  lodge  in  the  hole  and  grow  there. 
Persons  sometimes  catch  diphtheria,  tonsillitis,  and 
tuberculosis  because  a  few  germs  of  these  diseases 
lodge  in  a  decayed  tooth  and  multiply  there. 

Filling  Teeth.  -  -  You  may  save  a  decaying  tooth  by 
having  a  dentist  remove  the  decayed  part  and  fill  the 
hole.  The  filling  closes  the  hole  and  keeps  bacteria 
from  entering  the  dentine.  Have  a  dentist  examine 
your  teeth  every  few  months,  and  fill  each  hole  as  soon 
as  it  appears.  In  this  way  you  can  preserve  your 
teeth  for  a  lifetime. 

Care  of  the  First  Set  of  Teeth.  —  Two  sets  of  teeth 
grow  in  the  mouth  during  a  lifetime.  Those  of  the 
first  set  begin  to  drop  out  when  a  child  is  about  six 
years  old,  but  the  last  of  them  do  not  drop  out  until  he 


268 


CARE  OF  THE  NOSE  AND   MOUTH 


is  twelve  or  fourteen  years  old.  Some  of  these  first 
teeth  are  almost  sure  to  decay.  Few  children  have 
perfect  sets  of  teeth. 

Many  persons  think  that  the  decay  of  the  first  teeth 
does  no  harm.  Holes  in  the  first  set  of  teeth  are  as 
harmful  to  health,  and  are  often  as  painful,  as  holes 
in  the  second  set.  The  time  for  you  to  begin  to  care 
for  your  teeth  is  while  you  are  young.  It  is  as  neces- 
sary for  a  three-year-old  boy  to  brush  his  teeth  as  it  is 
for  a  thirty-year-old  man  to  brush  his. 

Sixth-year  Molar.  —  In  the  first  set  of  teeth  there 
are  only  two  double  teeth  on  each  side  of  each  jaw.  A 
third  double  tooth  appears  behind 
the  two  when  a  child  is  about  six 
years  old.  This  tooth  is  the  first 
tooth  of  the  second  set,  and  is  called 
the  sixth-year  molar.  Many  persons 
suppose  that  it  is  one  of  the  first 
set,  and  that  another  tooth  will  take 
its  place.  This  tooth  is  the  largest 
and  most  useful  of  all  the  double 
teeth,  and  if  it  is  lost,  no  other  tooth 
will  grow  in  its  place.  Take  care  of  it,  and  have  it 
filled  if  it  shows  any  signs  of  decay. 

Tartar  on  the  Teeth.  —  A  mineral  substance  called 
tartar  often  collects  upon  the  teeth,  and  forms  a  hard, 
brown  coating  near  the  gums.  This  substance  may 
push  the  gums  away  from  the  teeth,  and  may  cause 
the  teeth  to  become  loose.  Many  grown  persons  lose 


The  te^th  of  an  eight- 
y  ear-old  child. 
The  tooth  on  each 
end  of  the  half 
circle  is  a  sixth- 
year  molar. 


CARE   OF   THE   NOSE   AND   MOUTH  269 

their  front  teeth  because  they  allow  the  substance  to 
remain  on  them.  Brushing  the  teeth  helps  to  keep 
the  tartar  from  forming,  but  sometimes  it  is  necessary 
to  go  to  a  dentist  and  have  him  scrape  away  the  tartar 
next  to  the  gums. 

QUESTIONS 

Why  is  cleanliness  of  the  nose  and  mouth  necessary  for  the 
health  of  the  whole  body  ? 

What  are  the  white  spots  which  may  often  be  seen  on  the 
tonsils  ? 

What  danger  is  there  from  tonsils  which  are  full  of  holes  ? 

Of  what  use  is  the  mucus  which  is  produced  by  the  nose  ? 

How  may  the  nose  be  cleansed  ? 

How  does  the  use  of  a  handkerchief  affect  the  health  of  the 
body? 

How  may  the  mouth  be  cleansed  ? 

Describe  the  structure  of  a  tooth. 

What  is  the  cause  of  decay  in  a  tooth  ? 

How  may  the  teeth  be  prevented  from  decaying  ? 

Of  what  use  is  a  tooth  powder  in  brushing  the  teeth  ? 

How  do  decayed  teeth  help  to  spread  diseases  ? 

If  a  tooth  has  begun  to  decay,  how  may  it  be  saved  ? 
.  How  many  sets  of  teeth  grow  in  the  mouth  during  a  life- 
time? 

At  what  age  does  the  first  tooth  of  the  second  set  appear  ? 

In  what  part  of  the  jaw  should  you  look  for  the  first  tooth  of 
the  second  set  ? 

Why  should  a  tooth  of  the  first  set  be  filled  if  it  begins  to 
decay  ? 

What  harm  is  done  by  the  brown  substance   which  often 
forms  on  teeth  ? 


CHAPTER  XXVI 
INFECTIOUS   DISEASES 

Cause  of  Infectious  Diseases.  —  Those  forms  of 
sickness  that  are  caused  by  living  germs  growing 
in  the  body  are  called  infectious  diseases  (p.  41). 
Some  of  the  common  infectious  diseases  are  measles, 
scarlet  fever,  diphtheria,  typhoid  fever,  and  whooping 
cough.  Each  disease  is  caused  by  a  particular  kind  of 
germ  which  is  different  from  the  germs  of  all  other 
diseases.  If  we  are  not  sure  about  the  kind  of  disease 
which  a  person  has,  we  can  take  some  of  the  germs  from 
his  body  and  plant-  them  in  a  glass  tube,  or  in  a  lower 
animal,  where  they  can  multiply.  We  can  then  tell 
what  kind  of  germs  they  are. 

Fever.  —  Disease  germs  cause  sickness  by  producing 
poisons  called  toxins.  The  toxins  circulate  in  the  blood 
and  produce  a  fever  (p.  153).  A  fever  is  nearly  always 
caused  by  some  form  of  toxin  which  is  produced  by 
bacteria. 

Source  of  Disease  Germs.  —  Germs  of  disease  nearly 
always  come  only  from  some  person  or  animal  that  has 
an  infectious  disease.  We  often  say  that  they  come 
from  dirt  and  sewage,  but  no  disease  germs  would  be 
found  in  such  things  unless  they  were  first  put  there. 

270 


INFECTIOUS   DISEASES  271 

If  they  are  in  dirt,  or  sewage,  it  is  because  they  have 
escaped  from  a  sick  person  or  a  sick  animal.  A  pile  of 
dirt,  or  a  decaying  garbage  heap,  or  a  foul  cesspool, 
will  not  produce  any  kind  of  disease  germ,  unless  that 
kind  of  germ  is  first  planted  in  it. 

There  are  no  disease  germs  in  healthy  flesh  and  blood. 
A  person  will  not  have  an  infectious  disease,  unless 
disease  germs  which  grow  outside  of  his  own  body  are 
put  into  it.  Catching  a  disease  means  taking  its  germs 
into  the  body.  Taking  disease  germs  into  the  body  is 
called  infection. 

How  Disease  Germs  leave  the  Body.  —  Disease 
germs  leave  the  body  of  a  sick  person  in  five  ways. 
The  four  principal  ways  are  through  the  intestine, 
bladder,  nose,  and  mouth.  These  are  also  the  prin- 
cipal gateways  through  which  excretions  leave  the 
body  (p.  173).  Every  excretion,  except  perspiration, 
from  the  body  of  a  diseased  person  usually  contains 
germs  of  the  disease  (p.  176).  If  all  excretions  from 
the  sick  were  destroyed,  disease  germs  could  not  reach 
other  persons  to  infect  them. 

The  fifth  way  in  which  disease  germs  pass  off  from 
the  body  is  through  sores  on  the  skin.  The  germs 
very  seldom  pass  off  through  a  sound  skin,  but  the  skin 
often  becomes  soiled  with  mucus  and  saliva  from  the 
nose  and  mouth,  and  with  the  excretions  from  the  in- 
testine and  kidneys,  and  so  the  perspiration  and  skin 
of  a  diseased  person  may  also  be  the  means  of  spreading 
diseases  (p.  166). 


272  INFECTIOUS   DISEASES 

Disease  Germs  and  the  Breath.  —  Disease  germs 
do  not  pass  off  from  the  body  with  the  breath  during 
quiet  breathing.  But  when  a  person  coughs,  or  sneezes, 
or  blows  his  nose,  or  spits,  he  usually  expels  little 
drops  of  mucus  and  saliva,  and  these  may  contain 
disease  germs.  If  the  drops  become  dried,  the  germs 
may  float  in  the  air  with  the  dust  of  a  room,  and  may 
make  the  air  dangerous  for  breathing.  Air  which  is 
foul  and  dusty  may  be  the  cause  of  spreading  diseases 

(P-  139)- 

Disease  germs  also  rise  with  the  dust,  if  the  floor  con- 
tains saliva  and  other  excretions  from  a  diseased  person. 
Most  foul  air  is  dusty,  and  contains  disease  germs 
which  have  risen  with  the  dust. 

It  is  almost  impossible  to  find  disease  germs  in  the 
outdoor  air,  even  a  few  feet  from  a  person  who  has  an 
infectious  disease,  or  near  a  house  in  which  he  is  sick. 

Disease  Germs  and  Dirt.  —  Dirt  and  filth  will  often 
contain  disease  germs,  but  not  always.  There  are 
usually  no  disease  germs  in  fresh  ashes,  or  in  the  sand 
of  the  seashore,  or  in  the  dust  of  a  flour  mill,  or  in  the 
mud  of  a  mountain  brook.  The  kind  of  dirt  in  which 
they  will  be  found  is  the  dirt  made  by  the  bodies  of 
sick  persons.  Whatever  is  soiled  by  anything  that 
comes  from  a  diseased  person's  nose,  mouth,  intestine, 
or  bladder,  will  contain  the  germs  of  the  disease.  The 
principal  reason  for  keeping  ourselves  and  everything 
about  us  clean  is  to  be  free  from  disease  germs. 

Things  which  diseased  persons  handle  often  contain 


INFECTIOUS   DISEASES  273 

the  germs,  but  not  always.  If  their  hands  are  clean, 
there  will  be  no  germs  on  them,  and  they  will  not  leave 
the  germs  on  anything  which  they  touch.  But  what- 
ever diseased  persons  soil  with  the  excretions  from  their 
bodies  will  contain  disease  germs.  The  germs  will  be 
found  on  soiled  articles,  such  as  clothes,  bedding,  towels, 
handkerchiefs,  table  dishes,  and  toys.  If  these  things 
are  boiled  or  washed  well,  the  germs  on  them  will  be 
killed. 

Most  house  flies  are  carriers  of  disease  germs,  be- 
cause they  are  born  in  the  excretions  of  the  body,  and 
because  they  usually  live  on  filth  (p.  198). 

Impure  water  may  be  the  means  of  spreading  diseases 
if  it  contains  excretions  from  diseased  persons.  When 
it  is  the  cause  of  a  disease,  a  great  many  persons  in  a 
town  are  usually  made  sick  at  the  same  time,  for  a 
number  are  likely  to  use  the  same  water. 

Weather  and  Diseases.  —  Many  persons  suppose 
that  bad  weather  is  often  the  cause  of  diseases.  Hot 
weather  helps  the  growth  of  bacteria  in  food  and  filth. 
When  the  weather  is  wet,  or  cold,  or  stormy,  persons 
often  stay  in  closed  rooms  where  the  air  is  foul  and 
dusty,  and  contains  disease  germs.  These  are  the 
principal  ways  in  which  the  weather  helps  to  cause 
sickness  (p.  160). 

How  Disease  Germs  enter  the  Body.  —  The  two 
gateways  through  which  the  germs  of  most  diseases 
enter  the  body  are  the  nose  and  the  mouth.  None  of 
the  germs  of  the  common  infectious  diseases  can  enter 

GEN.   HYG. l8 


274  INFECTIOUS   DISEASES 

the  body  through  a  healthy  skin,  for  the  epidermis 
will  keep  them  out  if  it  is  sound  (p.  163).  Diseased 
persons  and  their  excretions  may  be  handled  with 
safety  if  there  are  no  cuts,  or  scratches,  or  sores  on  the 
skin. 

If  the  epidermis  is  injured  or  diseased,  germs  may 
pass  through  it  and  enter  the  blood  and  the  lymph. 
This  is  the  way  in  which  the  germs  of  pimples,  boils, 
and  sore  wounds  enter  the  flesh.  Malaria  and  yellow 
fever  are  caused  by  germs  which  are  put  into  the  blood 
by  the  bites  of  mosquitoes.  Hydrophobia  is  caused 
by  germs  which  are  put  into  the  flesh  by  the  teeth  of 
dogs  or  cats  which  have  the  disease. 

Contact  with  Diseased  Persons.  —  Diseases  are 
caught  directly  from  sick  persons  themselves  more 
often  than  in  any  other  way.  The  sick  often  give  the 
germs  to  others  by  kissing  them,  or  by  talking,  sneez- 
ing, coughing,  or  laughing,  while  their  faces  are  near  the 
faces  of  others  (p.  272).  They  also  spread  the  germs 
to  others  by  means  of  dishes,  bedclothes,  handker- 
chiefs, towels,  and  other  article's  which  they  use.  Com- 
ing into  close  contact  with  diseased  persons,  or  with 
toilet  articles  which  they  have  recently  used,  is  one  of 
the  principal  causes  of  infectious  diseases.  But  if  the 
sick  are  clean  and  do  not  place  their  faces  near  your 
face,  you  are  in  very  little  danger  of  catching  their 
diseases,  even  if  you  stand  near  them. 

How  the  Body  destroys  Disease  Germs.  —  Every 
person  often  takes  disease  germs  into  his  body  without 


INFECTIOUS   DISEASES  275 

catching  a  disease,  for  the  body  can  destroy  the  germs 
if  only  a  few  enter  it.  The  body  destroys  disease  germs 
in  two  ways.,  First,  the  white  blood  cells  seize  the 
germs  and  destroy  them  (p.  90). 

Second,  the  liquid  part  of  the  blood  contains  sub- 
stances which  hinder,  or  prevent,  the  growth  of  the 
germs.  Some  persons  have  a  larger  quantity  of  these 
substances  than  others,  and  so  they  escape  diseases 
which  others  catch.  But  nearly  every  person  will 
take  a  disease  if  a  great  number  of  germs  are  put  into 
his  body  at  once.  About  a  thousand  germs  must 
enter  the  body  at  one  time  in  order  that  any  of  them 
may  be  able  to  grow  and  produce  a  disease. 

The  power  of  destroying  disease  germs  in  the  body 
may  be  increased  by  anything  which  will  increase  the 
health  of  the  body.  Fresh  air,  good  food,  exercise, 
and  proper  rest  are  among  the  best  of  all  means  of  pro- 
tection against  infectious  diseases. 

Immunity.  — ;  A  person  who  has  had  measles,  or 
scarlet  fever,  or  chicken  pox,  or  smallpox,  or  mumps, 
or  whooping  cough,  or  yellow  fever,  will  not  have  the 
same  disease  a  second  time,  even  though  he  should 
take  the  germs  into  his  body.  As  soon  as  a  person 
catches  one  of  these  diseases  and  the  germs  begin  to 
grow  in  the  body,  his  blood  begins  to  form  a  new  sub- 
stance, called  an  antitoxin,  which  destroys  the  toxins 
of  the  germs,  and  prevents  those  kinds  of  germs  from 
growing.  The  body  will  afterward  keep  on  forming  the 
antitoxin  of  that  disease  during  the  rest  of  the  person's 


276  INFECTIOUS   DISEASES 

life,  and  no  more  of  the  germs  of  that  disease  will  be 
able  to  grow  in  his  body.  If  the  germs  of  a  disease  will 
not  grow  in  a  person's  body,  we  say  that  the  person 
is  immune  to  that  disease. 

Very  few  persons  are  naturally  immune  to  any  of 
the  common  diseases,  for  the  blood  does  not  begin  to 
form  the  antitoxin  against  a  particular  disease  until 
the  germs  of  that  disease  begin  to  grow  in  the  body. 
Nearly  every  child  catches  two  or  three  kinds  of  dis- 
eases before  he  grows  up,  and  is  afterwards  in  no  danger 
of  taking  those  particular  diseases  again. 

Vaccination.  —  Some  germs  of  a  disease  are  like 
weak  seeds  of  a  plant,  and  are  hardly  able  to  grow  at 
all.  If  these  weakened  germs  are  placed  in  the  body, 
they  make  very  little  growth  and  do  not  endanger 
health,  but  yet  they  cause  the  blood  to  form  the  anti- 
toxin of  the  disease.  Causing  the  body  to  form  an 
antitoxin  by  means  of  weakened  germs  is  called  vac- 
cination. ^ 

Vaccination  for  Smallpox.  —  Cows  sometimes  have 
a  mild  disease  called  cowpox.  The  germs  of  cowpox 
are  like  very  weak  germs  of  smallpox.  When  a  person 
is  vaccinated,  a  few  of  the  germs  from  a  calf  are  rubbed 
into  a  small  scratch  on  his  arm.  The  germs  grow  and 
cause  a  blister  or  sore  to  form  on  the  spot.  After 
two  or  three  weeks  the  spot  heals  and  leaves  a  scar. 
While  the  germs  are  growing  in  the  flesh,  they  cause 
the  blood  to  form  an  antitoxin  which  will  remain  in  the 
body,  and  will  prevent  smallpox  germs  from  grow- 


INFECTIOUS   DISEASES  277 

ing  if  they  should  enter  the  body.  One  vaccina- 
tion will  usually  protect  a  person  from  smallpox  for 
many  years,  arid  often  for  a  lifetime.  The  vaccinated 
persons  who  do  take  the  disease  have  it  very  mildly. 
A  good  rule  is  to  vaccinate  every  child  when  he  begins 
to  go  to  school,  and  again  at  about  the  age  of  twelve. 


IDEPARTMIHT  of  HtarcTHr,"CTTVT5?~73TwTon> 


Vaccine. 

Before  the  year  1800  smallpox  was  so  common  that 
everybody  expected  to  have  it,  and  more  persons  died 
from  it  than  from  any  other  disease.  About  that  year 
vaccination  was  discovered  by  an  English  doctor 
named  Edward  Jenher,  and  was  at  once  widely  used. 
Since  that  time  there  has  been  less  and  less  smallpox 
among  civilized  people.  Every  inhabitant  of  Germany 
is  vaccinated,  and  smallpox  is  almost  unknown  in  that 
country.  Many  people  in  the  United  States  have  not 
been  vaccinated,  and  the  United  States  has  about  a 
hundred  times  as  much  smallpox  as  Germany.  There 
is  almost  no  smallpox  in  New  York  city,  because  all 


278  INFECTIOUS   DISEASES 

school  children  in  the  city  and  nearly  all  grown  persons 
are  vaccinated. 

Some  persons  do  not  get  vaccinated  because  they 
fear  that  the  vaccination  will  produce  a  disease.  If 
the  arm  is  swollen,  or  if  the  vaccinated  person  is  made 
sick,  it  is  because  dirt  and  disease  germs  were  allowed 
to  enter  the  vaccinated  spot.  Pure  vaccine  germs  do 
not  cause  pain  or  sickness,  and  do  not  leave  any  harmful 
substance  in  the  body.  The  vaccine  that  is  now  supplied 
by  boards  of  health  is  pure,  and  is  put  up  in  sealed 
glass  tubes.  It  is  easy  to  put  the  vaccine  into  the 
arm  in  a  clean  and  safe  way.  Disease  germs  may  be 
kept  out  of  a  vaccination  sore  just  as  surely  and  readily 
as  they  may  be  kept  out  of  drinking  water,  or  out  of  a 
wound  which  a  surgeon  makes  at  an  operation.  If  this 
is  done,  vaccination  is  safe,  and  does  not  produce  any 
bad  results. 

Other  Forms  of  Vaccination. — Vaccinations  with 
the  dead  germs  of  typhoid  fever  are  used  for  protection 
against  typhoid  fever.  By  using  hydrophobia  germs 
that  are  dead  or  greatly  weakened,  the  body  may  be 
made  immune  to  hydrophobia.  Vaccines  are  also 
made  for  the  cure  of  boils  and  pimples,  and  other  forms 
of  blood  poisoning. 

Diphtheria  Antitoxin.  —  After  the  poisons  of  diph- 
theria germs  have  been  injected  repeatedly  into  a  horse 
for  about  three  months,  the  blood  of  that  horse  will 
contain  a  large  amount  of  an  antitoxin  which  will  pre- 
vent diphtheria  germs  from  growing  in  the  animal. 


INFECTIOUS   DISEASES  279 

Blood  which  is  drawn  from  the  horse  will  then  contain 
large  amounts  of  the  antitoxin.  This  is  the  way  of  ob- 
taining the  antitoxin  which  is  used  for  the  prevention 
and  cure  of  diphtheria  in  man. 

Diphtheria  antitoxin  is  not  poisonous  to  man.  If 
it  is  given  before  the  diphtheria  germs  have  nearly- 
poisoned  the  body  to  death,  it  will  cure  the  disease. 
Owing  to  its  use,  the  number  of  persons  who  die  from 
diphtheria  is  now  only  about  one  third  as  many  as 


Antitoxin  for  diphtheria. 

before  it  was  discovered.  If  the  antitoxin  is  given  to  a 
well  person,  no  diphtheria  germs  will  be  able  to  grow 
in  his  body  until  after  two  or  three  weeks.  For  this 
reason  it  is  often  given  to  nurses  who  care  for  the  sick. 

The  antitoxins  for  lockjaw,  meningitis,  cholera,  and 
snake  bite  poisoning  are  also  manufactured. 

Alcohol  and  Diseases.  —  Some  persons  take  alcoholic 
liquors  as  a  medicine,  thinking  that  they  will  prevent 
a  disease,  or  cure  slight  forms  of  sickness.  Alcohol  can 
neither  prevent  nor  cure  a  sickness,  for  it  weakens  the 
whole  body.  It  poisons  the  white  blood  cells,  and  pre- 


280  INFECTIOUS  DISEASES 

vents  them  from  destroying  disease  germs.  A  person 
who  drinks  is  more  likely  to  catch  a  disease  than  those 
who  let  alcohol  alone.  Drinkers  who  catch  pneumonia, 
or  typhoid  fever,  or  other  severe  illness,  are  much  more 
likely  to  die  than  those  who  do  not  drink.  Surgeons 
fear  to  operate  on  those  who  are  hard  drinkers. 

QUESTIONS 

What  is  the  cause  of  infectious  diseases  ? 

Name  some  of  the  common  infectious  diseases. 

Where  do  the  disease  germs  which  are  in  dirt  and  sewage 
come  from  ? 

What  is  infection  ? 

Through  what  four  natural  gateways  do  disease  germs  leave 
the  body  of  a  sick  person  ? 

Why  do  disease  germs  not  leave  the  body  through  a  sound 
skin? 

When  may  the  skin  of  a  diseased  person  contain  disease 
germs  ? 

When  may  the  expired  breath  of  a  diseased  person  contain 
the  germs  of  his  disease  ? 

What  are  the  two  gateways  by  which  disease  germs  usually 
enter  the  body  ? 

Name  some  places  in  which  you  may  expect  to  find  disease 
germs.  t 

When  is  the  air  likely  to  be  the  carrier  of  disease  germs  ? 

What  has  the  weather  to  do  with  the  spread  of  diseases  ? 

What  are  toxins? 

What  is  the  usual  cause  of  a  fever  in  the  body  ? 

What  substances  in  the  body  have  the  power  of  destroying 
disease  germs  ? 

What  is  immunity? 


INFECTIOUS   DISEASES  281 

What  is  an  antitoxin  ? 

What  is  "vaccination? 

For  what  disease  was  vaccination  first  done  ? 

How  is  a  person  vaccinated  for  smallpox  ? 

How  is  the  vaccine  for  smallpox  made  ? 

What  has  been  the  effect  of  vaccination  on  the  spread  of 
smallpox  ? 

Name  some  other  diseases  for  which  vaccines  are  prepared. 

How  is  diphtheria  antitoxin  prepared  ? 

What  has  been  the  effect  of  the  use  of  antitoxin  in  curing 
diphtheria  ? 

Name  some  other  diseases  for  which  antitoxins  are  prepared. 

What  is  the  effect  of  alcohol  on  the  power  of  the  body  to 
destroy  disease  germs  ? 


CHAPTER  XXVII 
PREVENTION  OF  INFECTIOUS   DISEASES 

Means  of  Defense  against  Disease  Germs.  —  Nearly 
all  kinds  of  infectious  diseases  may  be  prevented.  We 
know  the  source  of  their  germs,  how  they  enter  the 
body,  and  how  the  body  tries  to  destroy  the  germs 
which  enter  it.  We  have  two  methods  of  protecting 
ourselves  against  infectious  diseases :  first,  by  making 
our  bodies  as  immune  as  possible  to  the  germs  which 
may  enter  them  (p.  275) ;  second,  by  preventing  the 
germs  from  entering  our  bodies. 

Disposal  of  Excretions.  -  -  The  principal  source  of 
disease  germs  is  the  excretions  from  the  bodies  of  per- 
sons who  have  the  diseases.  The  proper  disposal  of 
all  excretions,  slops,  and  sewage  would  destroy  nearly 
all  disease  germs  before  they  could  reach  other  persons. 

Disease  germs  will  be  found  in  the  excretions  from 
the  noses  and  throats  of  those  who  have  infectious 
diseases.  An  excellent  way  to  dispose  of  these  ex- 
cretions is  to  catch  them  on  handkerchiefs  which  are 
to  be  boiled  or  burned  as  soon  as  they  are  soiled. 
Hold  a  handkerchief  to  the  mouth  and  nose  during 
coughing  and  sneezing,  so  as  to  catch  the, bits  of  liquid 

which  fly  off  (p.  139).     If  a  sick  person  is  in  bed,  do 

282 


PREVENTION  OF   INFECTIOUS   DISEASES         283 

not  tuck  his  handkerchief  under  a  pillow,  but  lay  it 
in  a  clean  dish  beside  the  bed. 

Disinfection/ —  Destroying  disease  germs  on  an 
object  is  called  disinfection.  The  face,  hands,  and  skin 
of  the  sick  person  and  the  hands  of  the  nurse  may  be- 
come soiled  with  excretions.  Cleanse  and  disinfect 
them  by  washing  them  with  soap  and  warm  water  as 
soon  as  they  become  soiled.  Then  dispose  of  the  slops 
as  you  would  the  excretions  of  the  intestine.  Bathing 
and  cleanliness  of  the  sick  are  very  necessary  in  pre- 
venting the  spread  of  diseases  (p.  166). 

After  you  have  cared  for  a  diseased  person,  there 
will  be  disease  germs  on  your  hands.  Wash  your 
hands  before  you  touch  anything  else.  Do  not  touch 
your  nose  or  mouth  until  your  hands  are  clean. 

The  dishes,  clothing,  and  towels  which  a  sick  person 
uses  will  be  soiled  with  the  excretions  from  the  nose  and 
mouth.  An  easy  way  to  free  the  soiled  articles  from 
the  germs  is  to  boil  them  at  once  after  using  them. 
Keep  a  kettle  of  water  boiling  on  a  stove,  ready  to 
receive  the  soiled  articles.  Anything  that  has  been 
boiled  may  be  handled  or  used  with  safety,  for  the  heat 
will  kill  all  the  disease  germs  that  may  have  been  on 
them. 

Some  persons  suppose  that  it  is  dangerous  to  change 
the  underclothing  or  bed  sheets  of  a  sick  person.  This 
is  not  so.  Soiled  clothes  are  dangerous  to  a  sick  person, 
for  he  may  take  the  germs  from  them  back  into  his 
own  body.  Change  the  clothing  and  sheets  every  day 


284         PREVENTION  OF  INFECTIOUS  DISEASES 

or  two,  or  as  often  as  they  become  soiled.  Keep  the 
floors  and  everything  else  about  the  room  clean,  so 
as  to  remove  all  traces  of  the  disease  germs. 

Fresh  Air  and  Sunlight.  —  Some  persons  suppose 
that  fresh  air  will  make  a  sick  person  catch  cold.  This 
is  not  so.  He  will  catch  cold  from  disease  germs, 
and  the  only  air  which  contains  them  is  that  which  is 
foul  or  dusty.  Fresh  air  will  help  to  prevent  a  person 
from  taking  cold,  even  though  the  air  feels  cool  (p.  139). 

Keep  a  window  in  the  sick  room  open  all  day  and 
all  night,  so  that  the  sick  person  and  those  who  care 
for  him  will  not  breathe*  disease  germs.  Keep  the 
window  shades  up,  and  let  the  sunlight  into  the  room, 
for  the  light,  falling  on  disease  germs,  will  kill  them 
in  a  few  minutes  (p.  150).  Place  a  screen  in  front  of 
the  sick  person  to  protect  him  from  uncomfortable 
drafts  and  his  eyes  from  the  bright  glare  of  the  sun. 

Disinfectants.  —  Substances  are  often  mixed  with 
excretions,  or  dissolved  in  the  water  of  the  laundry  or 
bath,  in  order  to  kill  disease  germs.  A  substance 
which  will  kill  disease  germs  is  called  a  disinfectant,  or 
antiseptic.  All  disinfectants  are  poisonous  to  the  body 
if  they  are  swallowed. 

One  of  the  best  of  all  disinfectants  is  a  solution  of 
formaldehyde.  Another  name  for  the  solution  is 
formalin.  A  tablespoonful  of  it  is  to  be  put  into  two 
or  three  pints  of  water,  and  used  for  washing  the  hands, 
floors,  furniture,  and  soiled  clothes  and  dishes,  and  for 
mixing  with  the  excretions.  It  is  not  to  be  used  for 


PREVENTION   OF   INFECTIOUS   DISEASES         285 

washing  the  face  for  fear  of  harming  the  eyes  and 
nose. 

Another  disinfectant  is  carbolic  acid.  It  is  a  deadly 
poison.  One  or  two  tablespoonfuls  of  a  weak  solution, 
well  mixed  with  a  quart  of  water,  may  be  used  for 
washing  the  hands  and  soiled  clothes  and  dishes. 

A  third  disinfectant  is  chloride  of  lime.  This  is 
used  principally  for  disinfecting  excretions.  It  must 
be  well  mixed  with  the  excretions  before  it  will  kill  the 
bacteria  in  them. 

Isolation.  -  -  There  is  always  danger  that  disease 
germs  may  escape  from  a  person  who  has  an  infectious 
disease.  In  many  diseases  it  is  necessary  to  keep  the 
sick  away  from  other  persons.  Keeping  the  sick  away 
from  well  persons  is  called  isolation. 

When  you  have  a  cold  or  other  infectious  disease, 
stay  away  from  school  and  other  meeting  places,  and 
remain  in  a  room  by  yourself.  Do  not  sleep  with  other 
persons,  or  put  your  face  near  their  faces.  Use  your 
own  handkerchiefs  and  towels,  and  do  not  let  any  one 
else  use  them.  Dispose  of  all  the  excretions  from  your 
body  in  a  safe  way. 

If  you  are  living  in  a  house  with  some  one  who  has 
measles,  or  scarlet  fever,  or  diphtheria,  or  other  bad 
form  of  infectious  disease,  stay  away  from  school  and 
other  meeting  places,  because  you  may  have  already 
caught  the  disease  and  are  ready  to  be  sick  with  it. 

Quarantine.  —  The  germs  of  such  diseases  as  scarlet 
fever,  smallpox,  and  diphtheria  are  hard  to  kill.  The 


286         PREVENTION  OF  INFECTIOUS   DISEASES 

diseases  are  dangerous,  and  many  lives  are  lost  each 
year  because  of  them.  The  laws  require  that  the  board 
of  health  of  a  town  or  city  shall  be  told  whenever  any 
one  in  the  place  has  one  of  these  diseases.  The  health 
officer  then  visits  the  house,  and  gives  orders  that  all 
persons  except  the  nurses  and  doctors  shall  keep  away 
from  the  sick  person.  The  officer  also  instructs  those 
in  the  house  how  to  prevent  the  spread  of  the  disease. 
He  usually  puts  a  notice  on  the  house  warning  visitors 
to  keep  away  from  it. 

Isolating  a  sick  person  and  the  house  in  which  he  is, 
by  order  of  the  health  officers,  is  called  quarantine. 
If  the  persons  who  are  quarantined  are  poor,  the  health 
officer  supplies  them  with  food  and  other  needful  things 
at  public  expense. 

At  the  end  of  the  time  of  quarantine,  the  health 
officer  sees  that  the  rooms  which  have  been  used  by 
the  sick,  and  everything  in  them,  are  disinfected. 
This  is  done  by  cleaning  them,  and  by*either  washing 
everything  in  them  with  a  disinfectant,  or  filling  the 
room  full  of  a  disinfecting  gas. 

Fumigation.  —  Disinfecting  a  room  by  means  of  a  gas 
is  called  fumigation.  The  gas  is  usually  made  either 
by  burning  sulphur,  or  by  vaporizing  formalin.  A 
large  quantity  of  gas  is  needed  in  order  to  do  any  good 
at  all.  Five  pounds  of  sulphur,  or  a  pint  of  formalin, 
are  needed  for  each  1000  cubic  feet  of  space  in  the 
room,  and  the  room  must  be  tightly  closed  to  prevent 
the  escape  of  the  gas. 


PREVENTION   OF   INFECTIOUS   DISEASES 


287 


Colds.  —  Any  mild  form 
of  infectious  disease  is  usu- 
ally called  a  ,cold.  Sore 
throat,  tonsillitis,  and  what 
is  called  a  cold  in  the  nose, 
are  all  caused  by  disease 
germs  which  are  caught 
from  other  sick  persons 
(p.  270).  The  bad  forms 
of  colds,  called  bronchitis, 
and  pneumonia,  are  caused 
by  germs  growing  in  the 

air  tubes  and  lungs.       Any  Bacteria  which  cause  a  cold. 

form  of  cold  may  be  caught  from  a  person  who  has  the 
disease. 

A  cold  is  apt  to  be  dangerous,  for  it  weakens  the 
body,  and  makes  it  likely  to  take  other  diseases  easily. 
If   you  have  a  cold,   stay  away 
^  from  other  persons,  and  destroy 

*t  the  excretions  of  your  nose  and 
mouth.  If  everybody  did  this, 
very  few  persons  would  catch 
cold. 

Mild  Forms  of  a  Disease.  - 
Scarlet  fever,  diphtheria,  small- 
pox, and  most  other  infectious 
diseases  are  often  so  mild  that 
the  sick  persons  do  not  go  to  a 
Bacteria  of  diphtheria.  doctor.  Either  they  do  not  no- 


tr«g 

„  m'~ 


288 


PREVENTION   OF   INFECTIOUS   DISEASES 


tice  any  signs  of  the  sickness  on  their  bodies,  or  else 
they  suppose   that   they  have   harmless    colds.     Yet 

these  persons  carry  the  germs 
of  the  disease,  and  may  give 
the  disease  to  others  in  a 
deadly  form. 

Many  sore  throats  are 
either  mild  diphtheria,  or 
scarlet  fever,  and  sometimes 
what  seems  to  be  a  mild 

£  tt**  1      J  *     chicken   pox  is    smallpox   in 

JfiJ*  LjJlyi*1* 

8-^ — ^^fl***^!    which    only   a    dozen    spots 

Bacteria  of  typhoid  fever.  may     appear     on      the      skm^ 

Sickness  will  spread  from  these  mild  forms  of  the  dis- 
eases as  readily  as  from  the 
severe  forms.  Those  who 
have  one  of  these  diseases  in 
a  mild  form  will  spread  the 
disease  more  readily  than  a 
person  who  is  sick  in  bed, 
for  those  who  seem  to  be  well 
usually  go  among  people, 
and  often  they  take  no  care 
of  their  excretions. 
Diphtheria.  —  In  order  to 

prevent   a    disease,  We   must     Bacteria    which    cause   boils 

be  able  to  tell  it  when  we  see  running  sores- 

it.     If  a  white  patch,  like  a  scab,  is  seen  on  the  back 

part  of  the  throat,  that  person  has  either  diphtheria  or 


PREVENTION   OF   INFECTIOUS   DISEASES         289 

tonsillitis.  Sometimes  the  only  sure  way  to  tell  the 
two  diseases  apart  is  to  rub  a  small  piece  of  cotton 
over  the  spot  so  as  to  get  some  of  the  disease  germs 
from  the  throat,  and  then  plant  the  germs  in  a  glass 
tube.  A  growth  of  disease  germs  made  in  this  way  is 
called  a  culture  (p.  270).  By  means  of  it  we  can  tell 
what  disease  a  person  has. 

Practice  opening  your  mouth  and  letting  some  one 
press  your  tongue  down  with  a  spoon  so  as  to  see  the 
back  of  your  throat,  for  the  only  way  of  telling  what  ails 
you  when  your  throat  is  sore  is  to  look  into  it,  or  take 
a  culture  from  it. 

If  you  have  diphtheria,  the  disease  may  be  overcome 
by  the  use  of  antitoxin  (p.  278). 

Scarlet  Fever.  —  If  a  person  is  suddenly  taken  sick 
with  vomiting  and  a  sore  throat,  and  the  next  day  the 
skin  on  his  chest  begins  to  be  red,  the  sickness  to  think 
of  is  scarlet  fever.  If  we  are  not  sure  what  it  is,  we  can 
tell  in  two  or  three  weeks,  for  at  that  time  the  epidermis 
on  the  skin  all  over  the  body  will  begin  to  peel  off  if 
the  disease  is  scarlet  fever. 

Scarlet  fever  is  a  dangerous  form  of  sickness.  Strict 
isolation,  quarantine,  and  disinfection  are  necessary 
in  every  case,  no  matter  how  mild  the  sickness  may 
be. 

Some  persons  suppose  that  there  is  a  difference  be- 
tween what  is  called  scarlet  rash  and  scarlet  fever. 
A  scarlet  rash  is  merely  a  mild  form  of  scarlet  fever, 
and  a  person  who  has  it  may  give  a  bad  form  of  scarlet 

GEN.   HYG.  —  IQ 


2QO         PREVENTION   OF   INFECTIOUS   DISEASES 

fever  to  another  person.  Scarlatina  is  the  name  used 
in  medical  books  for  scarlet  fever. 

Measles.  —  Measles  begins  like  a  cold  in  the  nose 
and  eyes.  After  about  four  days  the  skin  begins  to 
break  out  in  red  blotches.  The  germs  are  given  off 
from  the  nose  and  mouth  from  the  very  beginning  of 
the  disease,  and  the  sickness  is  often  spread  to  others 
before  the  sick  persons  know  that  they  have  the  measles. 
The  only  way  to  stop  the  spread  of  the  disease  is  to 
keep  the  sick  persons  at  home  and  isolated  as  soon  as 
they  show  signs  of  a  cold  in  the  nose  and  eyes. 

Many  persons  suppose  that  measles  is  not  a  dan- 
gerous disease,  and  so  they  do  not  try  to  prevent  its 
spread.  Yet  it  causes  more  deaths  than  scarlet  fever. 
Both  it  and  scarlet  fever  often  cause  the  kidneys,  the 
eyes,  and  the  ears  to  become  diseased.  Measles  is 
the  cause  of  dangerous  forms  of  pneumonia  in  many 
persons. 

Whooping  Cough.  —  Whooping  cough  is  often  sup- 
posed to  be  a  mild  disease,  but  it  is  the  cause  of  nearly 
as  many  deaths  as  scarlet  fever,  for  it  often  causes 
diseases  of  the  lungs.  Keep  every  child  who  has  it 
away  from  other  children  as  long  as  he  has  the  dis- 
ease. 

Hookworm  Disease.  —  In  the  warmer  parts  of  the 
United  States  there  is  a  kind  of  sickness,  called  the 
hookworm  disease,  in  which  there  is  paleness  and  a  great 
weakness  that  seems  like  laziness.  The  disease  is 
caused  by  worms  about  a  quarter  of  an  inch  long, 


PREVENTION  OF  INFECTIOUS  DISEASES          291 

which  live  in  the  upper  part  of  the  intestine  and  suck 
blood  from  its  mucous  membrane. 

The  hookworm  lays  eggs  which  pass  out  with  the 
excretions  and  hatch  in  the  soil.  The  young  worms 
are  microscopic  in  size.  They  usually  reach  the  in- 
testine of  the  sick  person  by  burrowing  through  the 
skin  of  his  feet.  The  disease  may  be  prevented  by 
cleanliness  and  by  proper  disposal  of  excretions  and 
sewage.  It  may  be  cured  by  the  use  of  a  medicine, 
called  thymol,  which  will  kill  the  worms  in  the  intestine. 

Typhoid  Fever.  -  -  Typhoid  fever  is  caused  by  the 
germs  of  the  disease  growing  in  the  intestine.  The 
germs  enter  the  body  through  the  mouth.  The  disease 
is  spread  by  means  of  excretions  from  the  sick,  or  of  sew- 
age containing  their  excretions.  One  of  the  principal 
causes  of  typhoid  fever  is  water  which  has  been  made 
impure  by  excretions  from  the  sick  (p.  187).  Another 
common  cause  is  house  flies  which  carry  the  germs 
from  the  sick,  or  their  excretions,  to  the  food  on  which 
they  alight.  Many  persons  catch  typhoid  fever  from 
neglect  to  cleanse  their  hands  after  caring  for  the  sick. 

Some  persons  have  a  mild  form  of  typhoid  fever, 
but  seem  to  have  only  a  stomach  ache  which  lasts  for 
several  days.  These  persons,  working  in  kitchens 
and  dairies,  are  sometimes  the  means  of  spreading  the 
disease  to  others. 

Disease  Germs  in  Wounds.  —  If  a  wound  is  sore  and 
a  creamy  liquid  runs  from  it,  we  sometimes  say  that  a 
person  has  taken  cold  in  the  wound.  If  the  skin  around 


292          PREVENTION   OF   INFECTIOUS   DISEASES 

the  sore  spot  is  red  and  swollen,  we  sometimes  say  that 
he  has  blood  poisoning.  Taking  cold  in  a  wound,  and 
blood  poisoning,  each  means  that  disease  germs  are 
growing  in  a  wound.  Boils  and  pimples  are  caused  by 
disease  germs  which  enter  the  flesh  through  injured 
hair  roots  (p.  170). 

Many  persons  and  animals  have  small  pimples  and 
sore  spots  on  their  skin  from  which  disease  germs  are 
allowed  to  escape,  and  so  the  disease  germs  that  cause 
them  are  scattered  in  nearly  every  place  where  men  and 
animals  are  found.  They  often  grow  in  the  mouths 
of  the  glands  which  produce  perspiration  and  oil,  but 
there  they  usually  do  little  harm.  But  if  the  skin  is 
wounded,  they  may  enter  the  flesh  and  grow.  The 
white  blood  cells  try  to  kill  the  disease  germs,  but  the 
disease  germs  usually  kill  many  of  the  blood  cells.  The 
creamy  liquid  that  runs  from  the  sore  spot  is  called 
pus,  and  consists  principally  of  white  blood  cells  which 
have  been  killed  by  the  disease  germs.  Pus  usually 
contains  living  disease  germs. 

Dressing  a  Wound.  —  If  a  wound  contains  no  disease 
germs,  it  will  quickly  heal  without  pain  or  soreness. 
Covering  a  wound  with  a  clean  dressing  will  prevent 
germs  from  entering  it. 

The  blood  which  flows  from  a  wound  will  help  to 
wash  away  dirt  and  disease  germs.  Washing  a  wound 
with  clean  water  will  also  help  to  cleanse  it.  Always 
use  water  that  has  been  boiled  in  order  to  kill  the  germs 
which  may  be  in  it. 


PREVENTION   OF  INFECTIOUS   DISEASES         293 

A  good  form  of  dressing  consists  of  clean  cotton 
cloth  torn  in  strips.  A  dressing  may  be  made  from  old 
sheets  or  underclothing  that  have  been  washed  and 
ironed.  Packages  of  cloth  already  prepared  for  a 
dressing  may  be  bought  at  drug  stores.  The  prepared 
cotton  called  absorbent  cotton,  which  is  sold  in  drug 
stores,  is  one  of  the 
best  forms  of  dress- 
ing. 

If  a  wound  is 
small,  dress  it  by 
winding  a  strip  of 
dressing  round  and 

round    the    part.       If  An  arm  neatly  bandaged. 

a  wound  is  a  large  one,  crumple  up  a  bunch  of  dress- 
ing and  lay  it  on  the  wound,  and  bind  it  in  place  with 
strips  of  bandage.  Change  the  dressing  daily. 

Germs  cannot  grow  readily  in  a  wound  which  is  dry, 
but  they  may  grow  readily  in  any  liquid  which  runs 
from  a  wound.  A  dressing  of  cloth  or  cotton  will  soak 
up  the  liquid  and  the  germs  that  are  in  it,  and  thus  will 
prevent  the  growth  of  the  germs. 

Sticky  salves  and  plasters  are  usually  dangerous 
dressings,  for  they  stick  to  the  skin  around  a  wound, 
and  prevent  the  escape  of  pus  and  other  liquids.  When 
they  are  used,  germs  grow  in  the  liquid  under  the  salve, 
and  make  the  wound  red  and  sore. 

A  Wet  Dressing.  —  If  a  wound  is  sore  or  contains 
pus,  keep  the  dressing  wet  with  water  which  contains 


294         PREVENTION  OF  INFECTIOUS   DISEASES 

a  disinfectant,  in  order  to  kill  the  germs  which  soak  into 
the  dressing.  A  teaspoonf ul  of  carbolic  acid  well  mixed 
with  a  quart  of  clean  boiled  water  makes  a  good  liquid 
for  wetting  a  dressing. 

Lockjaw.  -  -  The  disease  called  lockjaw,  or  tetanus,  is 
caused  by  a  kind  of  germ  that  enters  the  flesh  through 
wounds.  The  tetanus  germ  is  almost  the  only  kind 
that  will  naturally  grow  outside  of  a  living  body.  The 
germs  may  often  be  found  in  the  soil  of  gardens  and 
roads.  They  cannot  grow  in  the  body  if  air  touches 
them,  but  they  may  readily  grow  in  deep  wounds,  such 
as  would  be  caused  by  a  nail  thrust  deeply  into  the 
flesh.  The  germs  are  also  likely  to  grow  in  burns 
made  by  fireworks,  for  the  burned  flesh  keeps  the  air 
out  of  the  deeper  parts  of  the  wound. 

Lockjaw  may  usually  be  prevented  by  dressing  a 
wound  with  clean  dressings,  and  keeping  the  dressing 
soaking  wet  with  a  disinfectant,  such  as  water  con- 
taining carbolic  acid.  A  dose  of  lockjaw  antitoxin  will 
prevent  the  growth  of  lockjaw  germs,  if  any  should 
enter  a  wound. 


QUESTIONS 

What  is  the  principal  source  of  disease  germs  ? 
What  is  a  safe  way  of  disposing  of  the  excretions  from  the 
nose  and  throat  ? 

What  is  disinfection  ? 

How  may  the  hands  and  skin  of  a  sick  person  be  disinfected  ? 


PREVENTION  OF  INFECTIOUS   DISEASES         295 

How  may  the  dishes  and  clothing  of  a  sick  person  be  dis- 
infected ? 

Give  some  reasons  why  the  underclothing  and  sheets  of  a 
sick  person  should  be  changed  often. 

What  is  the  effect  of  sunlight  on  disease  germs  ? 

What  is  a  disinfectant  ? 

Name  some  good  disinfectants. 

How  should  formalin  be  used  to  kill  disease  germs  ? 

How  should  carbolic  acid  be  used  ? 

How  does  the  isolation  of  diseased  persons  prevent  the  spread 
of  infectious  diseases  ? 

What  harm  may  be  done  by  visiting  a  person  who  has  an 
infectious  disease  ? 

What  is  quarantine? 

How  does  a  health  officer  quarantine  a  house  ? 

How  should  a  room  be  disinfected  at  the  end  of  a  quarantine  ? 

How  should  a  room  be  fumigated  in  order  to  kill  disease 
germs  in  it  ? 

What  is  a  cold? 

What  is  the  cause  of  a  cold  ? 

What  is  a  great  danger  in  extremely  mild  forms  of  infectious 
diseases  ? 

What  signs  would  make  you  think  that  a  person  has  diph- 
theria ? 

What  is  a  culture? 

What  are  the  signs  by  which  scarlet  fever  may  be  recognized  ? 

Why  should  mild  cases  of  scarlet  fever  be  quarantined  ? 

When  a  person  is  coming  down  with  measles,  what  signs 
does  he  show  before  his  skin  breaks  out  ? 

What  dangerous  forms  of  sickness  are  often  caused  by 
measles  ? 

How  is  hookworm  disease  usually  spread  ? 

How  is  typhoid  fever  usually  spread  ? 

What  is  the  cause  of  taking  cold  in  wounds  ? 


296          PREVENTION   OF   INFECTIOUS   DISEASES 

What  is  pus? 

What  is  the  reason  for  dressing  a  wound  ? 
How  should  you  dress  a  wound  ? 
What  is  a  wet  dressing  ? 

How  does  a  wet  dressing  destroy  disease  germs  which  may  be 
in  a  wound  ? 

What  is  the  cause  of  lockjaw  ? 
How  may  lockjaw  be  prevented  ? 


CHAPTER  XXVIII 
TUBERCULOSIS 

Tuberculosis,  the  Modern  Pestilence.  —  In  former 
days,  when  little  was  known  about  the  causes  of  dis- 
eases and  their  prevention,  plagues  and  pestilences, 
such  as  smallpox,  scarlet  fever,  and  cholera,  used  to 
sweep  over  the  land  and  kill  large  numbers  of  the  in- 
habitants each  year.  We  now  know  how  to  keep  them 
from  spreading,  and  have  almost  wiped  out  those  dis- 
eases which  come  suddenly  and  kill  quickly.  Yet  one 
great  pestilence  is  still  among  us.  Tuberculos's,  or 
consumption,  is  a  disease  which  now  kills  125,000  per- 
sons each  year  in  the  United  States,  or  more  than  the 
number  of  soldiers  who  were  killed  in  battle  during  the 
Civil  War.  It  is  often  called  the  great  white  plague, 
because  it  is  very  common  among  white  races,  and 
because  those  who  have  it  become  pale,  and  slowly 
waste  away.  One  tenth  of  all  deaths  in  the  United 
States  are  due  to  it,  and  yet  it  may  be  prevented. 

Bacteria  of  Tuberculosis. — Tuberculosis  is  caused 
by  a  kind  of  bacteria  growing  in  the  body.  They 
grow  in  the  lungs  more  often  than  in  other  organs, 
for  they  usually  enter  the  body  by  means  of  air.  They 
sometimes  grow  in  the  bones  or  joints,  and  there  give 

297 


298  TUBERCULOSIS 

rise  to  forms  of  hip-joint  disease,  hunchback,  and  other 
troubles.  They  may  also  grow  in  the  brain,  the  skin, 
the  intestine,  and  in  most  other  parts  of  the  body. 
Tuberculosis  of  the  lungs  is  usually  called  consumption. 

Cows  may  have  tuberculosis,  and  the  germs  may 
then  be  found  in  their  milk.  The  flesh  of  diseased 
animals  may  also  contain  the  germs.  Government 
inspectors  are  sent  to  slaughterhouses  to  examine 
the  animals  that  are  killed,  and  to  destroy  meat  which 
contains  signs  of  the  germs. 

How  Tuberculosis  is  Taken.  —  A  person  catches 
tuberculosis  from  some  one  else,  or  some  animal,  that 
has  the  disease.  Very  few  of  the  germs  are  given  off 
by  the  breath  and  by  the  skin  of  a  consumptive  person, 
but  the  phlegm  that  is  spit  out  from  the  mouth  contains 
them.  Drying  and  freezing  do  not  kill  the  bacteria, 
and  when  they  are  blown  away  as  dust,  another  person 
may  breathe  them  and  catch  the  disease.  The  germs 
may  be  carried  to  food  by  house  flies.  The  bacteria 
sometimes  enter  the  body  through  pricks,  or  cuts,  and 
also  by  means  of  milk  or  meat  from  cattle  which  have 
the  disease. 

The  bacteria  do  not  grow  within  the  body  of  every 
one  who  breathes  them,  for  in  a  strong,  healthy  body 
the  white  blood  cells  destroy  them,  and  substances  in 
the  blood  prevent  their  growth.  But  if  a  great  number 
of  the  bacteria  enter  the  body  at  one  time,  the  blood 
may  be  unable  to  overcome  them  all.  If  the  body  is 
weakened  by  overwork,  or  by  indigestion,  or  a  cold, 


TUBERCULOSIS  299 

or  other  sickness,  the  bacteria  may  grow,  even  though 
only  a  few  enter  the  body. 

Signs  of  Tuberculosis.  —  A  person  who  has  con- 
sumption has  little  pain  and  feels  but  little  sickness  at 
the  beginning  of  the  disease.  He  usually  feels  tired, 
loses  weight  and  strength,  and  often  supposes  that  his 
feelings  are  due  to  hard  work.  He  usually  coughs  as 
if  he  had  a  cold.  Consumption  often  comes  on  because 
the  germs  of  a  cold  have  weakened  the  body  so  much 
that  the  germs  of  tuberculosis  can  grow  in  it  (p.  287). 
Having  a  cough  for  some  weeks,  and  losing  flesh  and 
strength,  are  two  common  signs  of  consumption. 

Another  sign  of  consumption  is  a  fever.  A  mild 
cold  does  not  usually  cause  a  fever,  but  if  a  person 
who  seems  to  have  had  a  cold  for  some  weeks  has  a 
fever  every  afternoon,  it  is  likely  that  he  has  germs  of 
tuberculosis  growing  in  his  lungs. 

Scrofula.  —  Children  sometimes  have  a  disease, 
called  scrofula,  in  which  the  lymph  glands  of  the  neck 
become  enlarged  and  form  hard  swellings.  The  swell- 
ings may  become  red  and  tender,  and  may  contain  pus. 
They  are  often  caused  by  tuberculosis  germs  which 
enter  the  glands  through  the  throat.  Adenoids  and 
enlarged  tonsils  are  two  common  throat  troubles  which 
allow  the  germs  to  enter  the  flesh  and  the  glands.  If 
the  disease  is  neglected,  it  may  produce  tuberculosis 
of  the  lungs. 

Tuberculosis  of  Bones.  —  A  bone  or  joint  that  has 
tuberculosis  is  swollen  and  tender,  and  the  bone  itself 


300  TUBERCULOSIS 

becomes  softened.  A  bone  or  joint  that  slowly  be- 
comes sore  and  swollen  probably  contains  the  germs  of 
tuberculosis.  The  hip  is  a  joint  in  which  tuberculosis 
often  occurs. 

How  Tuberculosis  Germs  are  Spread.  —  If  a  person 
has  consumption,  the  principal  way  in  which  germs  of 
the  disease  leave  the  body  is  in  the  mucus,  or  phlegm, 
that  is  spit  from  the  throat.  This  mucus  is  called 
sputum.  Consumptive  persons  usually  cough  often, 
and  spit  up  a  great  deal  of  sputum.  Thousands  of 
persons  who  have  the  disease  spit  upon  public  streets, 
and  on  the  floors  of  workrooms.  The  germs  become 
dried  and  float  in  the  air  as  dust.  For  this  reason  the 
dust  from  city  streets,  and  the  air  of  poorly  ventilated 
workrooms  usually  contain  the  germs  of  tuberculosis. 
Those  who  work  day  after  day  in  crowded  shops  are 
almost  sure  to  take  germs  of  tuberculosis  into  their 
bodies,  and  these  germs  are  likely  to  grow  if  the  work- 
men are  overworked  or  underfed. 

Spitting.  —  Spitting  on  pavements  and  on  floors  is 
one  of  the  principal  means  of  spreading  tuberculosis. 
Persons  often  have  consumption  without  knowing  that 
they  have  the  disease,  and  so  it  is  not  safe  for  any  one 
to  spit  on  pavements  and  floors.  Spitting  on  these 
places  is  so  dangerous  that  the  laws  of  most  states  and 
cities  forbid  it,  and  signs  are  posted  in  cars  and  public 
places  telling  of  the  punishment  which  may  be  given 
to  those  who  break  the  law. 

Disposal  of  Sputum.  —  If  those  who  have  consump- 


TUBERCULOSIS  301 

tion  will  catch  and  destroy  all  their  sputum,  they  may 
safely  go  among  other  persons.  While  they  are  away 
from  home,  they  may  catch  the  sputum  in  clean  hand- 
kerchiefs which  they  may  safely  carry  in  waterproof 
pockets.  They  may  then  kill  the  germs  by  boiling 
the  handkerchiefs  when  they  get  home.  While  the 
consumptive  person  is  at  home,  he  may  catch  his 
sputum  in  paper  cups,  and  burn  them  at  the  close  of  the 
day. 

Using  a  spittoon  is  almost  as  dangerous  as  spitting 
on  the  floor,  for  a  spittoon  cannot  be  cleaned,  but  flies 
may  crawl  over  it  and  carry  away  the  disease  germs  to 
other  persons. 

A  consumptive  person  will  often  soil  his  face*  and 
hands  with  sputum.  Cleanliness  of  the  skin  is  of  great 
importance  in  preventing  the  escape  of  the  germs. 

Contact  with  a  Consumptive.  —  The  most  frequent 
way  of  catching  tuberculosis  is  by  taking  the  germs 
directly  from  a  consumptive  person  by  such  means  as 
kissing,  sleeping  in  the  same  bed  with  the  sick,  drying 
the  face  on  the  same  towel,  and  eating  from  the  same 
dishes.  The  husbands,  wives,  and  children  of  con- 
sumptive persons  are  more  likely  to  catch  consumption 
than  others,  for  their  faces  often  come  close  to  the  faces 
of  the  sick,  and  they  often  use  the  same  toilet  articles 
that  the  sick  use.  But  consumptive  persons  may 
safely  live  among  their  families  if  they  are  cleanly, 
have  their  own  toilet  articles,  and  keep  their  faces  a 
foot  or  two  away  from  the  faces  of  others  (p.  272). 


302  TUBERCULOSIS 

Protection  against  Tuberculosis.  --You  can  protect 
yourself  against  tuberculosis  in  two  ways:  first,  by 
preventing  its  germs  from  entering  your  body;  and 
second,  by  keeping  your  body  so  healthy  and  strong 
that  the  germs  will  not  grow  in  it  if  you  should  take  a 
few  into  your  body. 

One  means  of  preventing  tuberculosis  germs  from 
entering  your  body  is  by  guarding  against  coming  into 
close  contact  with  a  consumptive  person.  Another 
way  of  preventing  germs  of  tuberculosis  from  entering 
your  body  is  by  avoiding  those  things  which  contain 
the  germs,  such  as  public  drinking  cups  (p.  194), 
toilet  articles  that  have  been  used  by  other  persons, 
impure  milk  (p.  255),  and  meat  from  diseased  cattle 
(p.  298). 

Any  means  which  will  make  your  body  strong  and 
healthy  will  also  help  it  to  overcome  the  germs  of  tuber- 
culosis which  may  enter  it.  Some  of  these  means  are 
deep  breathing  (p.  122),  exercise  and  rest  (p.  83),  and 
proper  eating. 

The  germs  of  tuberculosis  often  enter  the  body  by 
means  of  foul  and  dusty  air  which  is  breathed.  Foul 
air  is  also  one  of  the  principal  causes  of  weakness  and 
poor  health.  By  always  breathing  pure  air,  you  may 
prevent  tuberculosis  germs  from  entering  your  body, 
and  you  may  also  help  to  make  your  body  strong  enough 
to  overcome  the  germs.  The  chapter  on  ventilation  is 
important  in  connection  with  the  prevention  of  tuber- 
culosis (p.  144). 


TUBERCULOSIS 


303 


Curing  Tuberculosis.  —  Consumption  may  be  cured 
if  it  is  treated  early.  The  signs  of  cured  consumption 
may  be  found  in  over  half  of  the  bodies  which  are  ex- 
amined after  death.  Many  persons  get  well  from  con- 
sumption, and  never  know  that  they  have  had  the 
disease. 

Fresh  Air.  —  One  of  the  most  important  of  all  things 
in  curing  consumption  is  fresh  air  all  the  time,  day  and 

night.       The    sick    

must  have  it  even 
if  the  air  is  cold. 
Cold  air  is  not 
dangerous.  It  is 
not  even  uncom- 
fortable if  plenty 
of  clothing  is  worn. 
In  those  hospitals 
in  which  the  great- 
est number  of  con- 
sumptives get  well, 
the  sick  live  out  of 
doors  all  day,  and 
sleep  in  tents  or 
porches  which  are 
wide  open  to  the 
air. 


A  sleeping  porch. 


Sleeping  tents  are  made  in  which  the  consumptive's 
head  lies  in  an  open  window  while  his  body  is  in  the 
room. 


304  TUBERCULOSIS 

Good  Food.  —  Another  thing  which  will  help  a  con- 
sumptive person  to  get  well  is  good  food.  He  cannot 
build  flesh  and  strength  out  of  medicines,  or  out  of 
anything  else  than  food.  He  needs  all  the  good  food 
that  he  can  digest,  but  no  more.  Overfeeding  is  as 
harmful  to  a  consumptive  as  to  a  healthy  person.  He 
needs  meat,  eggs,  milk,  and  other  foods  that  may  be 
easily  digested,  and  are  also  rich  in  protein,  for  he 
must  build  new  flesh  like  a  child  (p.  211). 

Rest.  —  A  third  thing  which  a  consumptive  person 
needs  is  rest,  for  he  needs  all  his  strength  to  overcome 
the  germs  of  the  disease.  A  little  exercise  is  helpful, 
but  the  sick  person  must  not  get  tired. 

A  great  many  persons  die  of  consumption  because 
they  do  not  stop  hard  work  when  they  begin  to  be  sick. 
They  may  safely  do  as  much  work  as  their  strength 
will  allow  without  their  becoming  tired. 

Care  of  Sputum.  —  A  fourth  thing  which  a  consump- 
tive person  must  do  in  order  to  get  well  is  to  destroy 
the  germs  in  his  sputum.  A  person  who  has  consump- 
tion will  start  the  germs  growing  in  new  parts  of  his 
lungs,  or  flesh,  if  he  takes  them  back  into  his  body. 
Many  fail  to  get  well  because  they  are  uncleanly 'and 
do  not  take  care  of  their  sputum.  Sunshine  in  the 
room,  and  cleanliness  of  the  floors  and  furniture,  are 
also  necessary  in  order  to  kill  all  the  germs  that  are  in 
the  sick  room. 

Teaching  about  Tuberculosis.  —  If  all  persons  under- 
stood the  nature  of  tuberculosis,  they  would  try  to 


TUBERCULOSIS  305 

cure  themselves  early  in  the  disease.  One  of  the  most 
important  steps  in  both  the  prevention  and  the  cure  of 
the  disease  is  teaching  every  person  about  it.  Many 
cities  and  states  have  societies  which  send  out  printed 
instructions  about  consumption.  Some  states  have 
exhibitions  of  charts,  pictures,  and  models,  showing 
how  the  disease  may  be  prevented  and  cured. 

Sanatoriums.  —  Many  cities  and  counties  have  hos- 
pitals and  sanatoriums  for  the  care  of  persons  who  have 
consumption.  One  of  the  most  valuable  uses  of  these 
places  is  to  teach  the  sick  how  to  breathe,  how  to  cat, 
how  to  exercise,  and  how  to  live  in  the  best  way  to 
get  well  and  stay  healthy. 


QUESTIONS 

Why  is  tuberculosis  called  the  great  white  plague  ? 

Out  of  every  one  hundred  deaths  how  many  are  caused  by 
tuberculosis  ? 

What  is  the  cause  of  tuberculosis  ? 

If  a  person  has  tuberculosis,  from  what  part  of  the  body  does 
he  give  off  the  germs  of  the  disease  ? 

How  do  tuberculosis  germs  usually  enter  the  body  of  a  well 
person  ? 

What  are  some  of  the  first  signs  that  appear  when  a  person  has 
tuberculosis  ? 

What  is  scrofula? 

How  are  tuberculosis  germs  usually  spread  ? 

What  harm  is  done  by  spitting  on  pavements  and  floors  ? 

How  can  a  person  who  has  tuberculosis  destroy  the  germs  in 
his  sputum  ? 

GEN.    HYG.  —  2O 


306  TUBERCULOSIS 

How  may  the  germs  of  tuberculosis  be  prevented  from  enter- 
ing the  body  ? 

How  may  the  germs  of  tuberculosis  be  prevented  from  grow- 
ing in  the  body  after  they  have  entered  it  ? 

Name  some  things  which  will  aid  in  the  cure  of  tuberculosis. 

Of  what  use  is  fresh  air  in  curing  tuberculosis? 

How  much  food  does  a  person  who  has  tuberculosis  need  to 
eat? 

Of  what  use  is  rest  in  the  cure  of  tuberculosis  ? 

Why  is  the  destruction  of  the  sputum  necessary  in  curing  a 
person  of  tuberculosis  ? 

Give  some  reasons  why  every  person  should  learn  about  the 
prevention  and  cure  of  tuberculosis. 


CHAPTER  XXIX 


THE  NERVOUS  SYSTEM 

Need  of  a  Nervous  System.  —  Every  part  of  the  body 
must  have  help  from  other  parts  in  order  to  live.  The 
arm  cannot  live  unless  it  receives  blood  from  the  heart, 
food  from  the  stomach,  and  oxygen  from  the  lungs; 
and  it  cannot  work  unless  it  receives  orders  from  the 
brain.  Each  organ  must  help  all  the  rest  of  the  body, 
and  so  it  must  receive  directions  telling  it  when  to  act, 
and  how  much  to  do.  The  work  of  directing  the  actions 
of  the  different  organs  of  the  body  is  done  by  the  organs 
of  the  central  nervous  system. 

Central  Nervous  System.  —  The  principal  organs  of 
the  central  nervous  system  are  the  brain  and  the  spinal 
cord.  The  brain 
fills  the  top  of  the 
skull  above  the 
eyes  and  ears.  The 
spinal  cord  is  about 
as  large  around  as 
a  little  finger,  and 
is  about  half  as 
long  as  the  back- 
bone. It  hangs  in- 


Human  brain,  side  view. 


307 


3o8 


THE   NERVOUS   SYSTEM 


fl 


side  of  the  backbone,  and  extends  from  the  brain  about 
to  the  waistline.  The  brain  and  the  spinal  cord  are 
almost  as  soft  as  jelly ;  but  they  are  protected  from 
injury  by  the  heavy  bones  of  the 
skull  and  the  backbone. 

Nerves.  —  The  brain  and  spinal 
cord  are  connected  with*  all  the 
other  organs  of  the  body  by  threads 
of  flesh  called  nerves.  Twelve  pairs 
of  nerves  are  joined  to  the  lower 
part  of  the  brain,  and  thirty-one 
pairs  are  joined  to  the  spinal  cord. 
The  use  of  nerves  is  to  carry  mes- 
sages between  the  organs  of  the 
body  and  the  central  nervous 
system. 

Nerves  are  like  telephone  wires. 
The  stomach,  lungs,  muscles,  skin, 
and  all  other  parts  of  the  body,  are 
like  customers  who  have  telephones 
in  their  stores  and  houses.  The 
brain  and  spinal  cord  are  like  cen- 
tral telephone  stations  which  the 
customers  call  up  when  they  wish 
to  send  messages.  Nerves  do  not 

Spinal  cord. 

run  directly  from  one  organ  to  an- 
other, but  nearly  all  messages  between  the  organs  pass 
through  either  the  spinal  cord  or  the  brain. 

Nerve  Cells.  —  The  parts  of  the  brain  and  spinal 


THE   NERVOUS   SYSTEM 


3°9 


A  nerve  cut  across. 


cord  that  receive  and 

send  messages  are 

called  nerve  cells*    The 

nerve  cells  are  so  small 

that   they   cannot   be 

seen  without  a  micro- 

scope.     They  have 

small  bodies  and  long 

branching     arms. 

Some  of  these  branches 

are  the  nerves  which 

go  to  all  parts  of  the 

body.     Other  branches  of  the  cells  extend  to  other 

nerve  cells.     The  nerve  cells  are  like  the  operators  in  a 

central  telephone  station.     Their  use  is  to  receive  and 

to   send  messages  which  pass  between  the  different 

parts  of  the  body. 

The  brain  and  the 
spinal  cord  consist  of 
nerve  cells  and  nerves. 
That  part  which  con- 
tains nerve  cells  is  red- 
dish gray  in  color,  and 
is  called  gray  matter. 
That  part  of  the  brain 
and  spinal  cord  which 
consists  of  nerves  is 
white  in  color,  and  is 

Nerve  cells  of  the  brain.  Called     white     matter. 


3io  THE  NERVOUS   SYSTEM 

Gray  matter  covers  the  outer  part  of  the  brain,  but  it 
forms  the  central  part  of  the  spinal  cord.  Some  col- 
lections of  gray  matter  also  lie  in  the  lower  part  of  the 
brain. 

Motor  Nerve  Messages.  —  Most  of  the  messages 
which  nerve  cells  send  out  are  orders  to  do  something. 
Any  nerve  which  carries  messages  away  from  the  central 
nervous  system  is  called  a  motor  nerve.  There  are 
four  principal  kinds  of  motor  nerve  messages. 

1.  Some  of  the  motor  messages  are  orders  for  the 
cells  all  over  the  body  to  take  food  and  grow.     When  a 
muscle  is  exercised,  it  grows- large  because  the  spinal 
cord  sends  orders  for  it  to  take  a  large  quantity  of  food 
from  the  blood  in  order  to  do  its  work  well. 

2.  Some  of  the  motor  messages  are  orders  for  the 
glands  to  secrete  their  liquids.     When  the  stomach 
receives  food,  the  spinal  cord  sends  orders  for  the  glands 
to  manufacture  gastric  juice. 

3.  Some  of  the  motor  messages  are  orders  for  the 
involuntary    muscles    to    contract.     When    cold    air 
strikes  the  skin,  the  spinal  cord  sends  orders  for  the 
muscles  of  the  arteries  to  contract,  so  as  to  keep  the 
blood  away  from  the  skin. 

4.  Some  of  the  motor  messages  are  orders  for  volun- 
tary muscles  to  contract  (p.   81).     Every  motion  of 
a  muscle  is  ordered  by  the  nerve  cells.     If  no  orders 
reach  the  muscles,  a  person  cannot  move,  and  we  say 
that  he  is  paralyzed. 

Sensory  Nerve   Messages.  —  The  messages  which 


THE   NERVOUS   SYSTEM  311 

the  organs  send  to  the  brain  and  spinal  cord  are  called 
sensory  nerve  messages,  because  many  of  them  pro- 
duce feelings  or  sensations.  One  class  of  sensory 
messages  are  those  by  which  the  organs  tell  of  their 
need  for  food,  or  oxygen,  or  rest.  After  hard  exercise 
the  feeling  of  shortness  of  breath  is  the  message  by  which 
the  muscles  tell  the  brain  of  their  need  of  oxygen.  If 
it  were  not  for  the  sensory  nerve  messages,  the  brain 
and  spinal  cord  would  not  know  what  orders  to  send 
to  the  various  organs. 

Other  messages  that  the  organs  of  the  body  send  to 
the  brain  are  those  telling  about  things  which  are  out- 
side of  the  body.  These  messages  are  sensations  of 
touch,  sight,  hearing,  smelling,  and  tasting,  and  are 
called  the  five  senses. 

If  something  which  is  touching  the  body  harms  it, 
the  feeling  which  is  produced  is  one  of  pain  in  the  in- 
jured spot.  Pain  is  often  a  useful  feeling,  for  it  gives 
warning  of  danger  to  the  body. 

Conscious  Nerve  Actions.  —  Nerve  actions  may  be 
divided  into  two  classes:  first,  those  which  may  be 
felt,  called  conscious  nerve  actions;  and  second,  those 
which  may  not  be  felt,  called  unconscious  nerve  actions. 

We  are  usually  conscious  of  only  two  kinds  of  nerve 
actions:  first,  the  motor  messages  to  the  voluntary 
muscles ;  and  second,  the  sensory  messages  which  the 
brain  receives  through  the  five  senses.  Nearly  all 
other  nerve  messages  are  sent  and  received  without  our 
knowledge.  For  example,  we  are  usually  conscious  of 


312  THE  NERVOUS   SYSTEM 

sending  orders  for  the  movements  of  our  arms  and  legs, 
and  receiving  messages  of  sight  and  hearing;  but  we 
are  not  conscious  of  the  messages  which  order  the  flow 
of  gastric  juice,  or  of  the  messages  by  which  the  muscles 
tell  of  their  need  of  food.  The  number  of  unconscious 
nerve  actions  is  far  greater  than  those  of  which  we  are 
conscious. 

The  nerve  messages  of  which  we  are  conscious  are 
either  received  by,  or  are  sent  from,  the  nerve  cells  of 
the  gray  matter  in  the  upper  part  of  the  brain.  We 
therefore  say  that  the  upper  part  of  the  brain  is  the  seat 
of  consciousness,  and  of  the  mind.  These  cells  do  the 
work  of  thinking,  and  send  out  the  orders  for  voluntary 
movements. 

Unconscious  Nerve  Actions. --The  messages  which 
control  the  acts  of  secretion  and  growth,  and  the  move- 
ments of  the  voluntary  muscles,  are  either  received  by,  or 
are  sent  out  from,  the  nerve  cells  in  the  spinal  cord  and 
in  the  lower  part  of  the  brain.  These  actions  are  not 
under  the  control  of  the  mind,  but  they  go  on  whether 
a  person  thinks  about  them  or  not,  and  whether  he  is 
asleep  or  awake. 

When  the  nerve  cells  of  the  upper  part  of  the  brain 
are  injured,  as  by  a  blow  on  the  top  of  the  head,  a  per- 
son is  unconscious,  like  one  in  a  deep  sleep.  But  life, 
growth,  and  repair  of  the  body  may  still  go  on  if  the 
nerve  cells  of  the  spinal  cord  and  lower  part  of  the  brain 
are  in  good  order. 

Relation  of  Brain  and  Spinal  Cord.  —  The  gray  mat- 


THE   NERVOUS   SYSTEM 


313 


ter  of  the  outer  part  of  the  brain  is  like  a  man  who 
drives  an  automobile,  but  does  not  repair  the  car,  or 
keep  it  in  ordef.  The  work  which  the  driver  does  is 
like  the  conscious  work  of  the  brain. 

The  gray  matter  of  the  lower  part  of  the  brain,  and 
that  of  the  spinal  cord,  is  like  a  workman  who  sees  that 
the  car  is  repaired  and  kept  in  good  order,  but  does  not 
run  the  car.  The  work  which  the  repair  man  does  is 
like  the  unconscious  work  of  the 
spinal  cord  and  the  brain. 

The  Spinal  Cord  and  Voluntary 
Movements.  -  -  The  cells  of  the 
spinal  cord  and  of  the  lower  part  of 
the  brain  usually  act  only  in  answer 
to  messages  which  they  receive  from 
some  other  part  of  the  body.  Some 
of  the  messages  telling  them  to  act 
come  from  the  nerve  cells  of  the 
upper  part  of  the  brain.  When  a 
person  wishes  to  move  a  muscle, 
the  cells  of  his  brain  send  an  order 
to  the  cells  of  the  spinal  cord,  and 
they  repeat  the  message  to  the 
muscles. 

Reflex  Action  of  the  Spinal  Cord.    Diagram  of  the  course 

-  The  cells  of  the  spinal  cord  often      °f  nerve  messages  in 

T  T  .  voluntary  action. 

send  out  orders  in  answer  to  sen- 
sory messages   which  they  receive   from  the  organs 
of    the    body.       When    a    person    pricks    his    finger 


THE   NERVOUS   SYSTEM 

with  a  tack,  the  finger  sends  a  sensory  message  of 
pain  which  passes  through  the  spinal  cord  on  its 
way  to  the  brain.  The  cells  of  the  spinal  cord  at 
once  reply  to  the  message  by  ordering  the  muscles  ctf 
the  arm  to  take  the  hand  away  from  the  tack,  and  the 
finger  is  already  snatched  away  from  danger  by  the 
time  the  message  of  pain  reaches  the  brain. 

Sending  a  motor  nerve  message  as  a  result  of  a  sensory 
message  is  called  reflex  action,   because   the  sensory 


Diagram  of  the  course  of  nerve  messages  in  reflex  action. 

message  seems  to  be  reflected,  or  turned  back,  as  a  motor 
message. 

Nearly  all  the  messages  for  secretion  and  growth, 
and  for  movements  of  involuntary  muscles,  are  reflex 
messages.  For  example,  the  cells  of  the  spinal  cord 
do  not  send  orders  for  the  stomach  glands  to  produce 
gastric  juice  until  they  receive  word  that  food  is  in  the 
stomach.  They  order  the  arteries  of  the  skin  to  con- 
tract when  they  get  a  message  that  something  cold  is 
touching  the  skin. 

Sympathetic   Nervous   System.  —  The   spinal   cord 


THE   NERVOUS   SYSTEM  315 

does  a  great  deal  of  its  work  with  the  assistance  of  sets 
of  nerve  cells  called  ganglia.  The  principal  ganglia 
are  arranged  irf  a  double  row  of  twenty-three  pairs 
down  the  whole  length  of  the  backbone.  They  are 
about  the  size  of  grains  of  wheat  or  oats,  and  are  con- 
nected with  the  spinal  cord  by  means  of  nerves.  Other 
nerves  go  from  them  to  the  arteries,  and  to  the  organs 
of  digestion,  respiration,  and  excretion.  The  ganglia 
and  their  nerves  form  what  is  called  the  sympathetic 
nervous  system. 

The  ganglia  send  orders  to  the  organs  to  do  those 
kinds  of  work  which  go  on  slowly  and  steadily,  such 
as  the  contraction  of  the  arteries,  the  peristalsis  of  the 
stomach  and  intestine,  and  the  secretion  of  saliva  and 
gastric  juice.  They  have  very  little  nerve  power  of 
their  own,  but  they  get  most  of  their  power  from 
the  spinal  cord.  The  spinal  cord  itself  acts  in  a  quick 
and  forcible  way,  as  in  its  reflex  action  when  the  finger 
touches  a  tack.  The  ganglia  slow  down  the  messages 
of  the  spinal  cord  and  send  them  out  in  a  gentle  and 
continuous  stream.  For  this  reason  the  actions  on 
which  life  depends,  such  as  digestion,  circulation,  and 
excretion,  go, on  slowly  and  regularly,  and  are  not 
readily  disturbed. 

A  disorder  of  any  part  of  the  body  affects  other  parts 
through  the  sympathetic  nervous  system.  For  example, 
those  who  have  eye  troubles  often  suffer  with  headaches 
and  stomach  sickness.  Adenoids  in  the  throat  inter- 
fere with  the  growth  and  strength  of  the  whole  body, 


316  THE  NERVOUS   SYSTEM 

even  though  they  do  not  produce  pain  or  a  feeling  of 
sickness.  A  weakness  of  any  part  of  the  body  may 
prevent  other  parts  from  being  strong.  Do  not  neglect 
a  weakness  or  disorder  in  any  part  of  your  body. 


QUESTIONS 

Why  does  a  person  need  a  nervous  system  ? 

What  are  the  principal  organs  of  the  nervous  system  ? 

Where  is  the  brain  situated  ? 

Where  is  the  spinal  cord  situated  ? 

Where  are  nerves  found  ? 

Compare  nerves  with  telephone  wires. 

What  are  nerve  cells  ? 

Where  are  nerve  cells  found  ? 

What  is  the  gray  matter  in  the  central  nervous  system  ? 

Of  what  is  the  white  matter  of  the  central  nervous  system 
composed  ? 

What  are  motor  nerves  ? 

What  are  some  of  the  messages  that  are  carried  by  motor 
nerves  ? 

What  are  sensory  nerves  ? 

What  are  some  of  the  messages  that  are  carried  by  sensory 
nerves  ? 

What  are  conscious  nerve  messages  ? 

Name  some  nerve  messages  of  which  a  person  is  conscious. 

Name  some  unconscious  nerve  messages. 

What  is  reflex  nerve  action  ? 

Explain  the  nerve  action  which  takes  place  when  a  person 
jumps  after  pricking  his  finger  with  a  tack. 

What  part  does  the  spinal  cord  take  in  conscious  nerve  acts  ? 

Where  is  the  sympathetic  nervous  system  found  ? 


THE   NERVOUS   SYSTEM  317 

Of  what  does  the  sympathetic  nervous  system  consist  ? 

Over  what  actions  does  the  sympathetic  nervous  system  have 
control  ? 

Where  does  the  sympathetic  nervous  system  get  its  power  to 
act? 

Why  does  a  disorder  of  a  single  organ  affect  the  whole  body  ? 


CHAPTER  XXX 


THE   BRAIN 

The  Three  Parts  of  the  Brain.  —  The  part  of  the 
central  nervous  system  which  is  inside  of  the  skull  is 
called  the  brain.  The  greater  part  of  the  brain  is  a 

large  mass  which 
fills  almost  all  the 
space  under  the 
rounded  top  of  the 
skull.  This  part 
is  called  the  cere- 

C^pP^  })Yum.      Under  its 

hinder    end    is    a 
smaller  mass  called 
the  cerebellum. 
A   slender   stem 


Q£      nerye 


Human  brain,  underside. 

from  the  cerebrum  and  cerebellum  extends  downward, 
and  is  continued  outside  of  the  skull  into  the  back- 
bone. The  part  of  the  nerve  stem  which  lies  inside 
of  the  skull  is  called  the  medulla.  That  part  of  the 
stem  which  lies  outside  of  the  skull  is  the  spinal  cord. 
The  brain,  spinal  cord,  and  nerves  may  be  compared 
to  a  tree.  The  spinal  cord  and  the  medulla  are  like 

318 


THE   BRAIN  319 

the  tree  trunk.  The  nerves  which  go  from  the  spinal 
cord  to  all  parts  of  the  body  are  like  the  roots  of  the 
tree.  The  cerebellum  and  cerebrum  are  like  the 
rounded  top  of  the  tree. 

The  Medulla.  —  A  person's  medulla  is  about  as  wide 
and  half  as  long  as  his  little  finger.  Nerves  extend 
from  it  to  all  parts  of  the  head  and  neck,  just  as  nerves 
from  the  spinal  cord  extend  to  all  other  parts  of  the 
body. 

The  white  matter  of  the  medulla  consists  of  nerve 
threads  which  join  the  cerebrum  and  cerebellum  to 
the  spinal  cord.  Some  of  the  nerve  cells  of  the  gray 
matter  of  the  medulla  control  the  motions  of  the  muscles 
of  the  head  and  neck,  and  other  cells  have  some  control 
over  the  heart. 

A  small  group  of  nerve  cells  which  lie  near  the  center 
of  the  medulla  within  a  space  about  the  size  of  a  pea 
have  control  over  the  movements  of  breathing.  If 
these  cells  were  destroyed,  breathing  would  stop  at 
once,  and  death  would  occur  almost  instantly.  This 
part  of  the  medulla  is  sometimes  called  the  seat  of 
life. 

The  Cerebellum.  --  The  cerebellum  is  about  the  size 
of  a  large  hen's  egg.  Its  outer  part  consists  of  gray 
matter  whose  cells  control  the  movements  of  the 
muscles  in  balancing  the  body,  as  in  standing  or  run- 
ning. The  cells  also  cause  the  muscles  of  the  body  to 
act  in  a  regular  and  orderly  manner  when  making  a  num- 
ber of  quick  and  exact  motions,  as  in  playing  a  piano. 


320 


THE   BRAIN 


Human  brain,  upper  surface. 


The    Cerebrum. 

-  The  cerebrum 
is  about  five  times 
as  large  as  all  the 
rest  of  the  central 
nervous  system 
put  together.  It 
covers  the  rest  of 
the  brain,  and  is 
the  only  part 
which  is  seen  when 
the  rounded  top  of 
the  skull  is  removed.  It  consists  of  gray  matter  cover- 
ing a  central  mass  of  white  matter.  The  cells  of  the 
gray  matter  are  the  seat  of  the  mind,  and  of  conscious 
nerve  action  (p.  311). 
The  white  matter 
consists  of  nerve 
threads  which  con- 
nect the  nerve  cells 
with  each  other  and 
with  the  rest  of  the 
body. 

The  surface  of  the 
cerebrum  is  folded 
and  crumpled,  and 
looks  as  if  its  cover- 
ing of  gray  matter 
were  too  large  for  it. 


Human  brain  cut  in  two  crosswise. 


THE   BRAIN 


321 


Because  of  the  folding,  the  amount  of  gray  matter 
is  about  three  times  as  much  as  it  would  be  if  the 
brain  were  smooth.  A  child  is  born  with  a  very  few 
folds  on  its  brain,  but  as  its  mind  grows,  the  folds  on 
its  cerebrum  also  grow  in  number  and  size. 

The  Work  of  the  Mind.  -  -  The  mind  acts  by  means 
of  the  nerve  cells  of  the  cerebrum.  These  cells  do  three 
kinds  of  work:  first, 
they  receive  sensory 
messages  by  means 
of  the  five  senses  (p. 
311);  second,  they 
send  out  motor  mes- 
sages to  the  volun- 
tary muscles ;  and 
third,  they  think. 

Each  part  of  the 
brain  has  one  kind 
of  work  to  do.  The 
cells  in  the  part  of 
the  cerebrum  behind 
the  ears  receive  mes- 
sages through  the  five 
senses.  Those  just 

above  and  in  front  of  the  ears  send  out  orders  for  moving 
the  voluntary  muscles.  Those  in  the  front  part  of  the 
cerebrum  do  most  of  the  work  which  is  called  thinking. 

Memory  and  Thinking.  —  The  nerve  cells  of    the 
cerebrum  keep  a  record  of  the  messages  which  they 


Diagram  of  the  action  of  different  parts  of 
the  brain. 


GEN.    HYG. 21 


322  THE   BRAIN 

receive  and  send  out.  This  record  is  called  the  memory, 
and  the  messages  which  are  recorded  in  it  form  a  per- 
son's knowledge. 

A  person  can  look  over  the  messages  which  he  has 
stored  in  his  memory.  He  can  compare  them  with  one 
another  and  in  this  way  he  can  get  new  knowledge. 
This  work  of  the  mind  is  called  thinking.  Most  of  the 
work  of  thinking  is  done  by  the  nerve  cells  which  lie 
just  behind  the  forehead. 

Training  the  Mind.  -  -  The  nerve  cells  of  the  cerebrum 
have  many  branching  arms  which  extend  to  the  nerve 
cells  in  other  parts  of  the  brain.  By  means  of  these 
branches  a  nerve  cell  knows  what  other  cells  are  doing. 

Brain  cells  and  their  branches  grow  by  use,  just  as 
muscles  grow  by  exercise.  The  brain  cells  of  a  baby  are 
small,  and  their  branches  are  few  and  short,  but  the 
branches  grow  in  number  and  length  as  the  child's 
mind  grows.  Your  muscles  and  bones  will  stop  grow- 
ing when  you  are  about  twenty-five  years  old,  but 
your  brain  cells  may  grow  until  you  are  about  fifty  years 
old,  if  you  exercise  your  mind  and  train  it. 

When  you  stop  studying  and  thinking,  your  brain 
cells  stop  growing.  If  you  leave  school  when  you  are 
fifteen  years  old,  and  do  not  study  or  think  hard  after 
that  age,  your  brain  cells  will  also  stop  growing,  and  you 
will  always  have  the  mind  of  a  fifteen-year-old  child. 
But  if  you  study,  and  read,  and  think,  your  brain  cells 
and  your  mind  will  keep  on  growing  for  many  years 
after  your  bones  and  muscles  are  full  grown. 


THE   BRAIN  323 

When  you  read  a  book  about  a  bell  or  other  object, 
you  use  the  nerve  cells  which  think.  When  you  see  a 
bell,  or  hear  it,  you  also  train  the  nerve  cells  which  re- 
ceive messages  from  the  eyes  and  ears ;  and  when  you 
ring  a  bell,  you  train  the  nerve  cells  which  send  motor 
messages  to  your  hands.  Thus  you  may  train  your 
mind  by  seeing  and  hearing,  and  by  working  with 
your  hands,  as  well  as  by  reading. 

Most  mental  training  at  school  consists  in  teaching 
the  thinking  cells  which  lie  just  behind  the  forehead. 
But  you  will  not  be  educated  unless  the  cells  by  which 
you  send  motor  messages,  see,  and  hear,  also  receive 
training. 

Laboratory  work  in  school,  and  working  in  a  car- 
penter shop,  are  as  much  a  part  of  mind  training  as 
studying  a  book  or  listening  to  a  speech.  A  boy  who 
has  been  trained  only  from  books  at  school  or  college 
has  to  start  work  in  a  low  position  in  a  shop  or  store  in 
order  to  train  that  part  of  his  brain  which  was  not 
trained  at  school.  But  the  boy  who  has  trained  his 
forehead  cells  to  think  will  soon  be  able  to  train  the  rest 
of  his  brain. 

Habits.  —  When  you  recall  anything  to  memory,  the 
cells  of  your  brain  try  to  do  the  same  thing  that  they 
did  when  they  formed  that  memory.  When  you  think 
about  a  flower,  the  cells  which  receive  messages  of  sight 
recall  the  messages  which  they  have  received  about 
the  color  of  the  flower,  and  you  can  seem  to  see  the 
flower  again  even  when  you  close  your  eyes.  When 


324  THE   BRAIN 

you  recall  an  act  to  memory,  the  cells  which  sent  out 
the  orders  from  the  brain  when  the  act  was  done  want 
to  send  out  the  orders  again  when  you  think  of  the  act. 

After  your  brain  cells  have  done  an  act  a  few  times, 
they  often  try  to  repeat  the  act,  whether  you  wish  them 
to  do  so  or  not.  We  then  say  that  you  have  a  habit  of 
doing  that  act.  Every  person  forms  habits  in  his  work 
and  play.  Some  persons  form  habits  of  always  getting 
up  early,  eating  properly,  acting  politely,  and  speaking 
pleasantly.  All  these  are  good  habits. 

Forming  Good  Habits.  —  No  one  starts  life  with  any 
kind  of  habits,  either  good  ones  or  bad  ones.  You 
form  most  of  your  habits  while  you  are  young.  The 
good  habits  which  you  form  will  be  as  lasting  as  the  bad 
ones. 

Every  one  forms  habits  in  his  eating,  dressing,  speak- 
ing, thinking,  sleeping,  walking,  and  in  doing  all  the 
other  acts  of  everyday  life.  All  these  habits  have  an 
effect  on  the  health  of  the  body.  For  example,  the 
things  which  a  person  eats,  and  the  way  in  which  he 
eats  them,  are  among  the  principal  things  which  affect 
health.  Yet  most  grown  persons  eat  in  the  way  in 
which  they  formed  habits  of  eating  while  they  were 
young.  Those  whose  eating  habits  are  right  seldom 
have  indigestion  or  stomach  troubles. 

You  will  easily  fall  into  bad  habits  if  you  are  careless 
and  do  not  think  about  your  actions.  Some  boys  and 
girls  think  they  can  do  a  forbidden  thing  a  few  times 
without  forming  a  habit  of  doing  it.  There  is  danger 


THE   BRAIN  325 

in  doing  any  wrong  or  improper  act,  for  by  repeating  the 
act  you  will  do  it  more  and  more  readily  until  you  will 
do  it  without  thinking.  Do  not  begin  to  do  a  wrong 
or  improper  act  at  all. 

You  can  overcome  a  bad  habit  if  you  put  a  right 
habit  in  its  place.  The  cells  of  your  brain  will  slowly 
forget  a  memory  if  you  do  not  recall  it  to  mind.  If  you 
wish  to  overcome  a  bad  habit,  watch  yourself  and  do 
the  act  in  the  proper  way.  Your  brain  cells  will  then 
forget  the  wrong  way  of  doing  the  act,  and  you  will 
form  a  habit  of  acting  properly. 

Directing  the  Thoughts.  -  You  can  turn  your 
thoughts  to  anything  you  wish,  but  your  mind  can  do 
only  one  thing  at  a  time,  and  do  it  well.  When  you 
try  to  do  an  arithmetic  example,  you  forget  your  work 
if  you  look  out  of  the  window,  or  listen  to  a  noise,  or 
whisper  to  some  one.  If  you  have  a  hard  example  to 
do,  keep  your  whole  mind  on  your  work  until  you  finish 
it. 

You  can  compel  your  mind  to  think  of  a  single  subject 
for  many  minutes  or  hours.  A  good  scholar  will  not 
notice  the  sounds  and  sights  around  him,  and  will 
forget  his  feelings  of  hunger  and  thirst  while  he  is  get- 
ting his  lessons.  Every  person  who  has  a  strong  mind 
has  the  power  to  keep  his  whole  thought  on  a  single 
thing  for  hours  at  a  time.  One  of  the  principal  things 
which  you  learn  at  school  is  how  to  think  without  being 
disturbed  by  what  goes  on  around  you. 

Nervousness.  —  If  a  person  cannot  keep  his  mind 


326  THE   BRAIN 

on  a  single  thing  at  a  time,  but  is  easily  disturbed  by 
what  goes  on  around  him,  we  say  that  he  is  nervous. 
Some  persons  suppose  that  what  is  called  nervousness 
is  a  sign  of  a  strong  mind,  because  those  who.  are  nervous 
often  take  notice  of  slight  feelings,  sounds,  and  sights 
which  most  persons  do  not  notice.  No  person  can  think 
well  if  he  allows  himself  to  be  disturbed  by  what  he 
feels,  or  hears,  or  sees.  Nervousness  is  not  a  help, 
but  it  is  a  great  hindrance  to  thinking. 

Some  children  are  nervous  because  they  are  not 
trained  to  behave,  and  to  put  their  mind  to  their  work. 
Others  are  nervous  because  they  really  have  something 
the  matter  with  their  bodies.  Those  who  are  sick,  or 
tired,  or  in  pain,  are  nervous  because  they  do  not  feel 
well.  The  sickness  gives  them  about  all  the  unpleas- 
ant feelings  that  they  can  stand,  and  if  an  unpleasant 
sight  or  sound  is  added  to  their  feelings,  they  become 
cross  and  fretful.  A  child  who  has  a  stopped-up  nose, 
and  has  to  breathe  through  his  mouth,  is  likely  to  be 
cross  and  fretful,  for  he  always  has  an  uncomfortable 
feeling,  and  any  discomfort  added  to  it  makes  more  than 
the  child  can  stand. 

Other  common  causes  of  nervousness  in  children  are 
sitting  up  late  at  night,  indigestion,  improper  eating, 
adenoids,  and  foul  air.  These  things  are  also  causes  of 
ill  health.  Doing  the  things  which  make  .the  body 
healthy  and  strong  will  usually  prevent  or  cure  ner- 
vousness. 

Joy  of  Health  and  Strength.  —  A  person  who  is 


THE   BRAIN  327 

healthy  will  have  very  few  feelings  which  make  him 
think  about  his  body.  He  will  be  able  to  use  his  arms, 
and  legs,  and  all  the  rest  of  his  body  as  he  would  a 
machine  which  is  in  perfect  order.  Almost  the  only 
uncomfortable  feelings  that  he  will  have  will  be 
hunger,  thirst,  weariness  after  work,  and  other  feelings 
which  tell  him  what  his  body  needs.  He  will  work 
hard  for  the  pleasure  of  working,  and  will  put  forth  his 
strength  for  the  delight  of  using  it.  Children  and 
young  animals  play  until  they  are  tired  out,  because 
the  use  of  their  strength  is  a  joy  to  them. 

A  healthy  grown  person  wrill  enjoy  life  like  a  child. 
He  will  not  notice  the  slight  aches  and  pains  which 
come  while  he  works  and  plays,  but  he  will  enjoy  trying 
his  endurance  and  strength.  Even  his  hunger  and  his 
tired  feelings  will  not  be  unpleasant,  for  his  eating, 
his  rest,  and  his  sleep  will  be  among  the  greatest 
pleasures  of  the  day. 

Tired  Nerve  Cells.  —  When  nerve  cells  work,  they 
use  up  some  of  their  own  substance,  as  muscle  cells  do 
when  they  act.  After  a  few  hours  of  work  they  become 
small  in  size  and  unable  to  go  on  with  their  work. 
There  is  then  a  tired  feeling  like  that  which  conies  after 
muscular  work.  Nerve  cells  direct  the  actions  of  the 
muscles,  and  doing  muscular  work  tires  the  brain  as  well 
as  the  muscles.  Many  of  the  tired  feelings  after  exercise 
are  due  to  tired  nerve  cells. 

When  a  person  thinks  about  a  single  thing  day  after 
day,  the  nerve  cells  which  are  in  use  do  not  get  time  to 


328  THE   BRAIN 

rest.  A  scholar  who  thinks  about  his  examinations 
for  hours  and  days  does  not  allow  his  brain  cells  to  rest, 
but  he  comes  to  his  test  tired  out.  A  person  who 
worries  wears  out  his  brain  cells  by  thinking  about  his 
troubles  during  every  moment.  Any  one  who  sticks 
closely  to  only  one  kind  of  work  without  resting  will 
finally  ruin  his  health,  for  nerve  cells  need  to  rest  and 
to  store  up  food  just  as  muscles  need  rest. 

Nerve  Rest.  —  A  good  form  of  nerve  rest  is  a  change 
of  work,  for  it  brings  a  different  set  of  nerve  cells  into 
use,  and  allows  the  tired  cells  to  rest.  A  boy  who 
studies  hard  all  day  will  get  brain  rest  by  playing  base- 
ball after  school,  for  his  thinking  cells  will  rest  while 
he  uses  the  nerve  cells  with  which  he  directs  his  muscles. 
A  bookkeeper  who  sits  at  a  desk  all  day  may  get  brain 
rest  by  tending  a  garden,  or  driving,  or  taking  pho- 
tographs. A  tired  business  man  will  rest  his  brain 
while  he  drives  an  automobile  for  an  hour  or  two  at  the 
close  of  the  day. 

If  a  person  has  no  liking  for  play  or  pleasure,  his 
mind  will  always  be  thinking  about  his  work,  and  the 
nerve  cells  with  which  he  does  his  work  will  get  no  rest. 
It  is  a  good  thing  for  every  person  to  learn  to  like  some 
kind  of  play  or  pleasure,  for  during  playtime  the  work- 
ing cells  of  the  brain  will  rest. 

Play  is  also  of  great  value  because  it  often  exercises 
those  nerve  cells  which  are  not  put  to  use  during  the 
hours  of  work.  Many  persons  put  their  mind  upon 
their  business  so  closely  that  they  do  not  know  how  to 


THE   BRAIN  329 

look  at  a  beautiful  view,  or  how  to  listen  to  pleasant 
music,  or  how  to  saw  a  board.  Learn  to  enjoy  that 
kind  of  play  which  will  train  your  mind  as  well  as  give 
you  rest  and  pleasure. 

Sleep.  --  The  mind  gets  a  complete  rest  during  sleep, 
for  then  the  nerve  cells  of  the  cerebrum  seem  to  lose  their 
connection  with  the  rest  of  the  body.  But  the  spinal 
cord  and  the  medulla  act  as  perfectly  while  a  person  is 
asleep  as  while  he  is  awake.  The  object  of  sleep  is  to 
allow  the  nerve  cells  of  the  cerebrum  to  repair  their 
worn-out  parts  and  take  a  new  supply  of  food. 

Every  person  must  have  sleep.  He  can  go  without 
food  longer  than  he  can  go  without  sleep.  One  of  the 
first  signs  of  danger  from  overworking  the  mind  is 
trouble  in  sleeping.  This  is  because  the  nerve  cells 
have  formed  such  a  habit  of  working  every  moment 
that  they  cannot  stop  working  when  the  person  lies 
down  at  night. 

While  the  brain  is  at  work,  a  large  quantity  of  blood 
flows  through  it,  but  during  sleep  it  contains  only  a 
little  blood.  One  of  the  principal  things  which  prevent 
sleep  is  too  much  blood  in  the  brain.  When  you  can- 
not fall  asleep,  you  can  often  hear  your  pulse  beat  in 
the  ear  which  lies  on  the  pillow.  Anything  which  will 
cause  the  blood  to  leave  your  brain  will  help  you  to  fall 
asleep.  Soaking  your  feet  in  hot  water  will  cause  the 
blood  to  flow  to  your  feet  and  away  from  your  brain. 
Eating  a  light  lunch  will  cause  the  blood  to  flow  to  your 
stomach.  Having  some  one  rub  your  back  will  cause 


330  THE   BRAIN 

the  blood  to  flow  to  the  muscles  of  your  back.  Listen- 
ing to  some  one  reading  a  dull  book  will  keep  you  from 
thinking  about  your  work,  and  the  blood  will  then 
leave  your  brain,  and  you  will  feel  drowsy.  These 
are  some  simple  things  which  will  help  you  to  fall  asleep. 

Insanity.  -  -  The  brains  of  some  persons  do  not  act 
properly  on  account  of  injury  or  disease.  A  person 
who  cannot  take  care  of  himself  on  account  of  brain 
injury  or  disease  is  called  insane. 

An  insane  man  is  usually  able  to  do  most  brain  acts 
in  a  proper  way.  His  brain  is  like  a  printing  press 
which  is  perfect  except  in  one  or  two  parts,  and  which 
will  print  a  newspaper  if  the  printer  guides  the  paper 
through  those  imperfect  parts.  A  man  whose  brain 
is  unable  to  do  any  act  in  a  proper  way  is  called  an 
idiot. 

Most  insane  persons  show  their  insanity  only  when 
they  think  of  particular  things.  For  example,  some 
think  they  are  kings  wrongfully  kept  from  their  thrones. 
These  insane  persons  are  able  to  dress  properly,  to  care 
for  their  bodies  and  rooms,  and  to  read  and  understand 
the  newspapers.  They  are  dangerous  because  they 
are  likely  to  injure  other  persons  and  destroy  their 
property,  just  as  real  kings  do  when  they  go  to  war  for 
their  thrones. 

Causes  of  Insanity.  -  -  There  are  over  40,000  insane 
persons  in  the  hospitals  of  New  York  State.  About 
one  quarter  of  them  are  insane  because  of  alcoholic 
drink  or  the  use  of  opium.  Another  quarter  are  insane 


THE   BRAIN  331 

as  the  result  of  an  infectious  disease  which  affects  the 
whole  body.  Some  were  born  with  weak  minds  be- 
cause their  parents  had  Weak  minds. 

Many  persons  with  weak  minds  and  diseased  brains 
would  not  become  insane  if  they  did  not  overwork  their 
brains.  After  constant  worry  or  weeks  of  work  upon 
a  single  object,  the  brain  may  be  unable  to  change  its 
thoughts  or  direct  them  to  other  objects.  A  person 
with  such  a  brain  is  insane.  Vacations,  and  play  be- 
tween the  hours  of  work,  would  prevent  many  persons 
from  becoming  insane. 

Care  of  the  Insane.  —  If  a  person  has  an  injured  arm, 
the  principal  thing  to  do  for  it  is  to  give  it  entire  rest 
until  it  can  grow  strong  again.  The  principal  thing 
to  do  for  an  insane  person  is  to  prevent  his  brain  from 
doing  those  acts  which  it  cannot  do  properly.  This 
can  be  done  in  the  best  way  by  taking  the  person 
away  from  his  home  and  his  work,  and  placing  him  in 
a  hospital  where  new  thoughts  will  fill  his  mind.  Most 
insane  persons  improve,  and  many  recover,  within  a 
few  weeks  or  months  after  they  enter  a  hospital. 

Alcohol  and  the  Brain.  —  One  of  the  principal  effects 
of  alcohol  on  the  body  is  to  poison  the  nerve  cells  of  the 
brain.  This  is  what  is  meant  when  it  is  said  that  drink 
goes  to  the  head.  The  most  common  form  of  the  poison- 
ing is  drunkenness  (p.  53). 

When  a  person  drinks,  the  first  nerve  cells  to  be 
poisoned  are  those  with  which  thinking  is  done.  One 
of  the  first  signs  that  a  man  is  getting  drunk  is  that  he 


332  THE  BRAIN 

talks  without  thinking  how  his  words  sound.  This 
poisoning  begins  soon  after  the  alcohol  is  taken. 

The  next  brain  cells  to  be  poisoned  are  those  by  which 
the  muscles  are  moved.  In  this  stage  of  drunkenness 
a  person  cannot  walk  straight  or  talk  clearly. 

The  next  brain  cells  to  be  poisoned  are  those  by  which 
messages  are  received  through  the  senses.  The  drunken 
person  then  knows  nothing,  but  lies  as  if  in  a  deep 
sleep.  The  alcohol  may  also  poison  the  cells  in  the 
lower  part  of  the  brain,  and  life  is  then  in  danger,  for 
these  cells  control  the  breathing  and  the  heart. 

In  olden  times  men  used  to  have  drinking  contests 
to  see  who  could  drink  the  most.  It  was  thought 
that  the  winner  would  be  the  coolest  and  most  thought- 
ful person  in  times  of  accident  or  danger,  for  if  alcohol 
did  not  upset  his  thoughts,  it  was  supposed  that  nothing 
else  would  upset  them.  The  alcohol  often  dulled  his 
mind  and  thoughts,  and  the  drinker  would  then  per- 
form daring  acts.  The  reason  why  alcohol  seemed 
to  make  men  brave  and  cool  was  not  that  it  helped 
them  to  think,  but  that  it  kept  them  from  thinking 
clearly. 

If  alcohol  really  made  men  brave  and  thoughtful, 
it  would  be  given  to  firemen  when  they  go  to  dangerous 
fires.  But  one  of  the  strictest  rules  in  all  fire  depart- 
ments is  that  the  men  shall  not  drink,  for  the  kind  of 
thoughtless  daring  produced  by  alcohol  is  dangerous 
both  to  the  firemen  themselves  and  to  those  whom  they 
would  try  to  save. 


THE   BRAIN  333 

Effects  of  Light  Drinking.  —  After  the  brain  cells 
have  been  slightly  injured  over  and  over  again,  they  can- 
not recover  frorh  the  harm.  Taking  alcoholic  liquors 
injures  the  mind,  even  though  not  enough  alcohol 
is  taken  at  any  one  time  to  produce  drunkenness.  The 
first  signs  that  a  drinker  is  harmed  are  usually  shown 
by  his  carelessness  in  his  work. 

Drinkers  lose  their  keenness  of  judgment,  and  often 
make  mistakes  in  their  work.  If  a  drinker  were  the 
cashier  of  a  bank,  he  would  be  likely  to  add  columns  of 
figures  wrong.  It  would  not  be  safe  for  a  drinking 
man  to  run  a  locomotive  engine,  and  the  officers  of  a 
railroad  will  not  employ  a  drinking  man  anywhere  on 
the  road  if  they  know  it.  Many  men  lose  good  posi- 
tions because  of  strong  drink,  and  men  who  have  great 
abilities  often  fail  to  secure  good  positions  because  they 
are  drinkers. 

Alcohol  and  Poverty.  -  -  The  use  of  alcohol  often 
makes  men  poor.  They  lose  good  positions  on  account 
of  not  being  able  to  do  their  work  well.  They  spend 
their  money  for  drink  instead  of  for  food,  and  clothes, 
and  houses. 

A  place  where  the  effects  of  drinking  may  be  seen  is 
at  an  almshouse  where  poor  persons  who  are  too  weak 
to  work  are .  supported  at  public  expense.  Over  a 
quarter  of  all  those  who  live  in  the  poorhouses  of  the 
United  States  are  there  on  account  of  drink. 

Alcohol  and  Crime.  —  Another  place  where  the  effects 
of  drinking  may  be  seen  is  in  a  prison.  From  one 


334  THE   BRAIN 

quarter  to  one  half  of  all  the  persons  in  the  jails  and 
prisons  of  the  United  States  are  there  because  of  drink. 
Many  criminals  take  whisky  to  make  themselves  daring 
enough  to  commit  their  crimes.  Some  who  would 
not  be  dishonest,  if  they  were  alone,  are  led  to  commit 
crimes  by  other  criminals  whom  they  meet  in  saloons. 
Others  commit  crimes  because  the  drink  takes  away 
their  thoughts  and  prevents  them  from  seeing  the  bad- 
ness of  their  acts.  In  some  counties  where  the  sale 
of  strong  drink  has  been  forbidden  the  jails  are  almost 
empty. 

Alcohol  and  Insanity.  —  A  third  place  where  the 
effects  of  steady  drinking  may  be  seen  is  in  a  hospital 
for  the  insane.  Alcoholic  drink  is  one  of  the  most 
common  of  all  the  causes  of  insanity.  Nearly  a  quarter 
of  all  insane  persons  have  been  ruined  in  mind  by 
alcohol.  Many  insane  persons  are  the  children  of 
drinking  parents,  and  were  born  with  weak  minds 
because  of  their  parents'  drinking. 

Cigarettes  and  the  Mind.  -  -  The  use  of  tobacco  hin- 
ders the  growth  of  the  cells  of  the  brain.  Tobacco  is 
a  narcotic  to  the  nerve  cells  of  both  the  old  and  the 
young,  but  it  is  a  far  worse  poison  to  young  persons, 
than  to  grown  persons,  because  it  prevents  the  nerve 
cells  from  growing.  Very  few  boys  who  smoke  ciga- 
rettes stand  well  in  their  classes  at  school.  Nearly  all 
boy  criminals  use  cigarettes.  Most  of  the  idle  boys 
who  stand  on  street  corners  are  cigarette  smokers. 
When  we  see  a  boy  smoking  cigarettes,  we  think  of 


THE   BRAIN  335 

boys  who  are  idle,  or  dull,  or  bad.  A  boy  who  smokes 
a  cigarette,  or  who  uses  tobacco  in  any  other  form,  is 
harmed  as  much  as  a  grown  man  is  harmed  by  alcohol. 


QUESTIONS 

Into  what  three  parts  is  the  brain  divided  ? 

What  is  the  size  and  shape  of  the  medulla  ? 

What  is  the  use  of  the  medulla  ? 

Why  is  the  medulla  sometimes  called  the  seat  of  life  ? 

Where  is  the  cerebellum  situated  ? 

What  is  the  use  of  the  cerebellum  ? 

Where  is  the  cerebrum  situated  ? 

What  is  the  size  of  the  cerebrum  ? 

Where  is  the  gray  matter  of  the  cerebrum  ? 

Of  what  use  are  the  folds  on  the  surface  of  the  cerebrum  ? 

What  part  of  the  brain  does  the  conscious  work  of  the  mind  ? 

What  are  the  three  principal  kinds  of  work  which  are  done 
by  the  nerve  cells  of  the  cerebrum  ? 

In  what  part  of  the  cerebrum  are  the  nerve  cells  with  which  a 
person  feels,  sees,  and  hears  ? 

In  what  part  of  the  cerebrum  are  the  nerve  cells  which  send 
orders  to  the  voluntary  muscles  ? 

What  is  memory  ? 

What  takes  place  in  the  brain  when  a  person  thinks  ? 

In  what  part  of  the  cerebrum  are  the  nerve  cells  with  which 
thinking  is  done  ? 

What  happens  to  nerve  cells  when  the  mind  is  trained  ? 

What  is  a  habit? 

How  are  good  habits  formed  ? 

How  may  bad  habits  be  overcome  ? 

What  is  nervousness  ? 

What  are  some  of  the  causes  of  nervousness  ? 


336  THE   BRAIN 

How  do  tired  nerve  cells  differ  in  appearance  from  rested 
cells  ? 

How  does  a  change  of  work  help  to  rest  nerve  cells  ? 

What  makes  nerve  cells  tired  during  muscular  exercise  ? 

Of  what  value  is  play  to  a  business  man  ? 

What  is  the  use  of  sleep  ? 

What  are  some  of  the  reasons  why  a  person  cannot  fall 
asleep  when  he  lies  down  at  night  ? 

What  are  some  of  the  things  which  will  help  a  person  to  fall 
asleep  ? 

What  parts  of  the  brain  are  poisoned  when  a  person  is  made 
drunk  by  alcohol  ? 

What  effect  does  light  drinking  have  on  a  person's  mind  ? 

What  effect  does  drinking  have  on  a  person's  getting  employ- 
ment? 

What  effect  does  drinking  have  on  a  person's  power  to  earn 
money  ? 

What  effect  does  drinking  have  in  causing  crime  ? 

What  effect  does  drinking  have  in  producing  insanity  ? 

What  effect  does  tobacco  have  on  the  brain  cells  of  young 
persons  ? 

What  effect  do  cigarettes  have  on  the  minds  of  boys  who 
smoke  ? 


CHAPTER  XXXI 

THE   SENSES 

Use  of  the  Senses.  -  -  The  principal  nerve  messages 
of  which  a  person  is  conscious  are  those  which  are 
received  through  the  senses  (p.  311).  They  consist 
of  messages  of  touch,  smell,  taste,  hearing,  and  sight. 
Their  principal  uses  are  to  give  the  mind  a  knowledge 
of  what  goes  on  outside  of  the  body,  and  to  tell  a  person 
about  his  safety  and  comfort. 

Touch.  -  -  The  sense  of  touch  is  produced  by  the 
pressure  of  objects  upon  nerves  that  lie  just  beneath 
the  epidermis  of  the  skin  (p.  163).  If  the  epidermis 
is  removed,  anything  that  touches  the  skin  produces 
a  feeling  of  pain  or  smarting. 

The  sense  of  touch  gives  the  mind  a  knowledge  of 
the  size,  shape,  hardness,  smoothness,  weight,  and 
warmth  of  objects  which  touch  the  skin.  The  parts  of 
the  body  in  which  the  sense  of  touch  is  the  keenest  are 
the  ends  of  the  fingers  and  the  tip  of  the  tongue. 

One  way  of  testing  the  sense  of  touch  is  to  prick  the 
skin  with  the  sharp  points  of  a  pair  of  compasses.  The 
skin  of  the  back  will  seem  to  feel  only  a  single  point  if 
the  tips  of  the  compasses  are  separated  two  inches. 
The  ends  of  the  fingers  can  feel  that  the  points  are 

GEN.   HYG. 22  337 


338  THE   SENSES 

separated  if  the  points  are  only  one  eighth  of  an  inch 
apart. 

Weight.  —  A  person  judges  the  weight  of  an  object 
in  two  ways :  first,  by  the  feeling  of  touch  and  pressure 
which  the  object  gives  when  he  holds  it  in  his  hand ; 
and  second,  by  the  feeling  which  he  has  in  his  muscles 
when  he  lifts  it. 

False  Messages.  -  -  The  nerves  of  feeling  go  from  the 
skin  to  the  spinal  cord,  and  then  to  the  brain.  If  a 
nerve  is  wounded  anywhere  in  its  length,  the  feeling 
seems  to  be  at  its  outer  end,  and  not  at  the  place  where 
it  is  hurt.  What  is  called  the  funny  bone  is  a  nerve 
which  lies  just  above  the  inner  side  of  the  tip  of  the 
elbow.  If  it  is  pinched  at  the  elbow,  there  is  a  feeling 
of  pricking  and  smarting  in  the  little  finger  where 
the  nerve  starts. 

When  sitting  with  the  legs  hanging  down  from  the 
edge  of  a  chair,  the  foot  often  tingles  and  feels  heavy 
and  "  asleep,"  because  the  nerves  which  go  from  the 
foot  to  the  spinal  cord  are  pinched  at  the  knee.  At  the 
beginning  of  hip-joint  disease  the  pain  is  usually  felt 
in  the  knee,  and  in  appendicitis  the  pain  often  seems 
to  be  over  all  the  lower  part  of  the  body.  The  part 
in  which  a  pain  is  felt  is  not  always  the  part  which  is 
out  of  order. 

Training  the  Sense  of  Touch.  --You  can  train  the 
sense  of  touch  by  use.  Surgeons  train  their  finger 
tips  in  the  examination  of  parts  which  lie  deep  in  the 
body.  Blind  persons  learn  to  read  by  passing  their 


THE   SENSES  339 

finger  tips  over  raised  letters.  When  you  train  your 
sense  of  touch,  you  train  the  nerves  under  the  skin  to 
receive  slight  impressions.  You  also  train  the  cells 
of  your  brain  to  recognize  slight  differences  in  the  mes- 
sages which  they  receive.  Training  the  sense  of  touch 
is  excellent  mental  training. 

Smell.  -  -  Tiny  bits  of  matter  are  always  passing  into 
the  air  from  everything  which  has  an  odor  or  smell. 
When  these  bits  of  matter  touch  the  nerves  of  the  nose, 
they  give  rise  to  a  message  which  the  brain  receives  as 
a  smell.  By  means  of  the  sense  of  smell  a  person  can 
judge  of  the  purity  of  food  and  air.  Dogs,  and  some 
other  lower  animals  which  have  a  keen  sense  of  smell, 
depend  upon  it  in  the  same  way  that  persons  depend 
upon  the  sense  of  sight. 

Taste.  —  When  a  substance  which  has  a  taste  is 
taken  into  the  mouth,  some  of  it  dissolves  in  the  saliva 
and  soaks  through  the  epidermis.  When  it  touches  the 
nerves  of  the  tongue,  it  gives  rise  to  a  message  which 
the  brain  cells  receive  as  a  taste.  The  sense  of  taste 
enables  a  person  to  judge  the  purity  and  wholesome- 
ness  of  food.  The  taste  of  food  also  has  a  great  effect 
on  the  flow  of  gastric  juice,  and  on  the  digestion  of 
food  (p.  229). 

A  person  judges  the  tastes  of  sweetness  and  sourness 
by  means  of  the  nerves  in  the  front  part  of  the  tongue. 
He  judges  bitterness  and  saltness  by  means  of  the  nerves 
in  the  back  part  of  the  tongue.  He  judges  the  taste  of 
spices  largely  by  means  of  particles  which  rise  to  the 


340  THE   SENSES 

nose  and  there  produce  an  odor.  A  person  who  has 
a  cold  in  the  nose  loses  a  part  of  his  sense  of  taste, 
because  of  the  hindrance  to  his  sense  of  smell. 

Hearing.  —  One  way  in  which  a  person  learns  about 
objects  which  do  not  touch  the  body  is  by  means  of 
rapid  air  waves  which  are  set  in  motion  by  the  objects 
when  they  stir.  These  air  waves,  striking  the  nerves 
of  the  ear,  produce  the  messages  which  the  brain  receives 
as  sounds.  An  object  is  heard  only  when  it  moves, 
for  if  it  does  not  move,  it  does  not  produce  waves  in 
the  air.  Loud  sounds  are  caused  by  strong  air  waves 
which  are  sometimes  felt  with  the  nerves  of  the  skin, 
but  the  only  waves  which  are  heard  are  those  which 
strike  the  nerves  of  the  ears. 

The  Ears.  --The  ear  consists  of  three  parts,  called 
the  outer  ear,  the  middle  ear,  and  the  inner  ear. 

The  outer  ear  consists  of  two  parts:  first,  the  shell, 


Photograph  of  the  bones  of  a  human  ear.     a,  eardrum;   b,  bones  of  the 
middle  ear ;  c,  inner  ear. 


THE   SENSES 


341 


which  is  usually  called  the  ear ;  and  second,  a  tube 
which  extends  from  the  shell  of  the  ear  about  an  inch 
into  the  side  of  the  head.  The  bottom  of  this  tube  is 
closed  by  a  thin  sheet  of  flesh  called  the  eardrum. 

A  space  called  the  middle  ear  is  hollowed  out  of 
hard  bone  behind  the  eardrum.     The  middle  ear  is 


•INNER 
EAR 


EADRUM 

Diagram  of  the  ear. 

filled  with  air,  and  contains  a  chain  of  three  small  bones 
which  extend  across  it  from  the  eardrum  to  a  smaller 
drumhead  on  the  opposite  side. 

A  small  space  called  the  inner  ear  is  hollowed  out 
of  the  hard  bone  behind  the  inner  drumhead.  The 
inner  ear  is  shaped  like  a  snail  shell  and  is  filled  with 
a  liquid  in  which  the  nerves  of  hearing  lie. 


342  THE   SENSES 

How  a  Sound  is  Heard.  —  Air  waves  strike  the  ear- 
drum, and  cause  it  to  move  back  and  forth.  This 
moves  the  bones  of  the  middle  ear,  and  they  produce 
waves  in  the  liquid  of  the  inner  ear  which  strike  the 
nerves  of  hearing.  The  nerves  carry  a  message  of  the 
motion  to  the  brain,  and  the  brain  cells  receive  the 
message  as  a  sound. 

Deafness.  —  If  a  person  cannot  hear  well,  we  say 
that  he  is  deaf.  Deafness  is  nearly  always  caused  by 
some  trouble  in  the  middle  ear. 

A  tube  called  the  Eustachian  tube  extends  from  the 
middle  ear  to  the  throat.  If  you  hold  your  nostrils 
closed,  and  try  to  blow  hard,  you  will  force  air  into 
the  middle  ear.  You  will  then  feel  a  buzzing  in  your 
ear,  and  will  not  be  able  to  hear  well,  for  the  pressure 
of  the  air  will  keep  the  eardrum  from  moving  freely. 
When  you  swallow,  you  open  the  tube  and  let  the  air 
out  of  the  middle  ear,  and  you  can  then  hear  well 
again. 

Most  deafness  is  caused  by  throat  trouble  which 
stops  up  the  Eustachian  tube.  For  this  reason  ade- 
noids are  often  the  cause  of  deafness.  Most  children 
who  are  deaf  have  adenoids,  and  removing  the  adenoids 
will  nearly  always  help  their  hearing  (p.  128)'. 

Running  Ears.  —  Sometimes  a  soreness  and  swelling 
in  the  throat  extend  up  the  Eustachian  tube  into  the 
ear.  The  ear  then  becomes  filled  with  a  thick  liquid, 
like  that  which  is  coughed  from  the  threat.  This  liquid 
presses  upon  the  eardrum  and  causes  an  earache.  If 


THE   SENSES  343 

the  drum  bursts,  the  pain  will  stop  as  soon  as  the  mat- 
ter runs  out.  But  some  matter  will  often  keep  on 
running  from  the  ear  for  days  and  weeks  afterward. 

A  child  who  has  earache  and  running  ears  is  nearly 
always  deaf.  Most  of  these  children  may  be  made  well, 
and  their  deafness  cured,  by  a  skillful  physician. 

Testing  the  Hearing.  —  Many  children  seem  to  be 
dull  and  careless  at  school  because  they  are  slightly 
deaf  and  do  not  hear  what  is  said  to  them.  In  many 
schools  the  hearing  of  every  scholar  is  regularly  tested. 

A  good  way  to  test  a  person's  hearing  is  to  stand 
about  ten  feet  away  from  him  and  whisper  numbers  for 
him  to  repeat.  In  this  way  you  can  find  out  how  loud 
a  sound  he  can  understand.  Test  each  ear  separately 
while  the  other  ear  is  closed. 

A  person  with  good  hearing  will  be  able  to  under- 
stand a  loud  whisper  in  a  quiet  room  about  twenty-five 
feet  away  from  his  ear.  If  he  can  understand  a  loud 
whisper  no  farther  away  than  five  feet,  his  hearing  is 
only  one  fifth  as  good  as  it  should  be.  It  is  a  good  plan 
for  a  person  with  good  hearing  to  stand  beside  the  one 
whom  you  are  testing,  so  as  to  compare  the  hearing 
of  the  two. 

Training  the  Hearing.  —  Most  sounds  are  made  up 
of  many  separate  sounds.  The  sound  of  the  music 
made  by  a  singing  class  is  made  by  a  number  of  persons, 
and  a  trained  musician  can  pick  out  the  sound  of  each 
separate  voice.  The  same  sounds  fall  upon  the  ears 
of  all  who  listen  to  the  music,  but  the  trained  person 


344  THE   SENSES 

will  notice  differences  between  sounds  which  seem  alike 
to  untrained  persons.  Training  the  ears  is  really  train- 
ing the  brain  to  notice  slight  differences  in  the  messages 
which  the  ears  send  to  the  brain. 

Injuries  to  the  Ears.  —  The  middle  ear  and  the  inner 
ear  are  hollow  spaces  deep  in  a  hard  bone  of  the  skull, 
and  are  seldom  injured  except  by  blows  which  injure 
the  whole  skull.  Almost  the  only  way  in  which  an  ear 
is  likely  to  be  injured  is  by  thrusting  something  against 
the  eardrum.  Picking  the  ears  in  a  careless  way,  or 
putting  things  into  the  outer  ear  in  fun,  may  injure 
the  eardrum.  Slapping  or  boxing  the  ears  may  also 
injure  the  eardrum  by  producing  a  sudden  pressure  of 
air  upon  it. 

Earwax.  —  A  brown  wax  is  formed  by  the  skin  which 
lines  the  outer  half  of  the  tube  of  the  outer  ear.  The 
use  of  the  wax  is  to  protect  the  lining  of  the  outer  ear. 
The  epithelium  of  the  skin  grows  outward  and  carries 
the  wax  with  it,  and  there  is  seldom  need  to  pick  the 
wax  from  the  ears.  If  it  should  collect,  it  may  be 
removed  safely  by  means  of  the  loop  of  a  fine  wire 
hairpin. 

QUESTIONS 

What  are  the  senses? 

Of  what  use  are  the  senses  ? 

In  what  part  of  the  body  is  the  sense  of  touch  produced  ? 

In  what  part  of  the  body  is  the  sense  of  touch  the  keenest  ? 

How  can  you  test  the  sense  of  touch  ? 


THE   SENSES  345 

What  sense  do  blind  persons  use  when  they  read  ? 

How  do  you  judge  the  weight  of  an  object  ? 

Explain  the  unpleasant  feeling  which  you  have  in  your  little 
finger  when  you  pinch  your  funny  bone. 

Explain  the  feeling  which  you  have  in  your  foot  when  it  is 
asleep. 

How  is  the  sense  of  smell  produced  ? 

Of  what  use  is  the  sense  of  smell  ? 

How  is  the  sense  of  taste  produced  ? 

Of  what  use  is  the  sense  of  taste  ? 

What  kinds  of  taste  do  you  judge  with  the  front  part  of  your 
tongue  ? 

What  kinds  of  taste  do  you  judge  with  the  back  part  of  your 
tongue  ? 

How  does  the  sense  of  smell  help  you  to  judge  the  taste  of  an 
object  ? 

How  does  a  bell  or  other  object  produce  a  sound  ? 

Of  what  does  the  outer  ear  consist  ? 

What  are  the  principal  parts  of  the  middle  ear  ? 

What  are  the  principal  parts  of  the  inner  ear  ? 

How  does  sound  travel  from  the  outer  ear  to  the  nerves  of 
hearing  ? 

What  is  the  Eustachian  tube  ? 

How  does  throat  trouble  produce  deafness  ? 

How  do  adenoids  produce  earache  ? 

How  can  you  test  the  hearing  of  a  person  ? 

How  can  you  train  the  hearing  ? 

How  does  brain  training  help  the  hearing  ? 

How  may  slapping  the  ears  injure  the  hearing  ? 

How  may  earwax  be  removed  from  the  ears  with  safety  ? 


CHAPTER  XXXII 
THE  EYE 

Importance  of  Sight.  -  -  The  principal  way  in  which 
we  learn  about  an  object  which  is  beyond  our  reach  is 
by  means  of  light  which  comes  from  it  to  our  eyes. 
If  our  sight  were  suddenly  taken  away,  few  of  us  could 
carry  on  our  daily  work.  We  would  prefer  to  lose 
almost  any  other  part  of  the  body  rather  than  an  eye. 

The  Eyeball.  -  -  The  framework  of  the  eye  is  a  thick 
and  tough  shell  called  the  eyeball.  The  eyeball  is 
shaped  like  a  hollow  globe,  and  is  filled  with  a  clear 
liquid.  It  is  white  except  its  front  part  which  is  clear, 
like  glass,  and  is  called,  the  cornea. 

The  Iris.  -  -  The  eyeball  has  a  dark-colored  lining, 
called  the  choroid  coat,  which  is  about  as  thick  as  writ- 
ing paper.  The  front  part  of  this  lining  hangs  like  a 
curtain  behind  the  cornea,  and  is  called  the  iris.  The 
color  of  the  iris  is  usually  some  shade  of  blue  or 
brown.  It  shows  through  the  cornea,  and  gives  the 
eye  its  blue  or  brown  color. 

The  Pupil.  —  In  the  center  of  the  iris  there  is  a  round 
hole,  called  the  pupil,  through  which  light  enters  the 
eye.  The  pupil  appears  black  because  the  inside  of 
the  eye  is  dark  in  color.  The  iris  contains  muscles 

346  • 


THE   EYE  347 

which  regulate  the  size  of  the  pupil.  A  strong  light 
causes  the  muscles  of  the  iris  to  contract  and  make  the 
pupil  small  in  Border  to  shut  out  some  of  the  light. 
When  the  light  is  dim,  the  muscles  relax  and  the  pupil 
becomes  large  so  as  to  admit  as  much  light  as  possible. 
The  pupil  of  a  cat's  eye  is  only  a  narrow  slit  in  the  day- 
light, but  at  night  it  is  a  large,  round  hole  which  admits 
much  more  light 
than  the  pupil  of  a 
person's  eye.  For 
this  reason  a  cat 
can  see  at  night 
better  than  a  per- 

"The    Lens. -A 

rounded    piece    of 

•  Diagram  of  the  eye. 

tough  flesh,  called 

the  lens,  lies  just  behind  the  pupil.  It  is  as  clear  as 
glass,  and  its  front  and  back  faces  are  curved  like  the 
faces  of  a  small  magnifying  glass.  Its  use  is  to  bend 
rays  of  light  in  such  a  way  that  they  come  together 
upon  the  back  of  the  eyeball,  and  there  form  a  picture 
of  objects  which  are  in  front  of  the  eye. 

The  Retina.  —  A  large  nerve  called  the  optic  nerve 
enters  the  back  part  of  the  eyeball  and  spreads  over 
the  choroid  coat.  This  coating  of  nerves  is  called  the 
retina.  When  light  falls  upon  the  retina,  its  nerves 
carry  a  message  of  sight  to  the  brain. 

The  Eye  like  a  Camera.  —  An  eye  is  like  a  pho- 


348  THE  EYE 

tographer's  camera.  The  eyeball  is  like  the  camera  box. 
The  choroid  coat  is  like  the  black  paint  with  which  the 
inside  of  the  camera  is  coated.  The  cornea  and  the 
lens  are  like  a  double  lens  in  the  camera.  The  retina 
is  like  the  plate  on  which  the  picture  is  formed. 

Focusing  the  Eye.  —  When  a  photographer  takes  a 
picture,  he  moves  the  lens  back  and  forth  until  the  image 
is  distinct  upon  the  back  part  of  the  camera.  If  the 
image  of  a  distant  object  is  distinct,  the  image  of  an 
object  near  the  camera  will  be  blurred.  Adjusting  a 
camera  to  make  a  distinct  image  of  an  object  is  called 
focusing. 

The  eye  is  naturally  focused  to  form  a  distinct  image 
of  an  object  which  is  over  twenty  feet  away.  When  a 
person  looks  at  an  object  which  is  nearer  than  twenty 
feet,  muscles  inside  the  eyeball  make  the  lens  more 
curving  or  bulging,  in  order  to  form  a  distinct  image 
upon  the  retina. 

Reading  often  tires  the  eyes,  because  the  muscles 
of  the  eyes  have  to  act  upon  the  lens  in  order  to  form 
clear  images  of  the  print.  When  your  eyes  become 
tired  from  study,  you  may  rest  them  by  looking  at  the 
view  from  a  window,  for  the  muscles  which  focus  your 
eyes  are  at  rest  while  you  look  at  distant  objects. 

Blurred  Sight.  —  A  person  who  has  good  sight  can 
focus  his  eyes  to  see  an  object  which  is  only  six  inches 
away.  Some  persons  can  see  distant  objects  clearly, 
but  their  eye  muscles  are  unable  to  make  the  lens  curv- 
ing enough  to  see  objects  close  by.  These  persons  are 


THE  EYE  349 

called  farsighted.  The  lenses  of  their  eyes  are  not  suffi- 
ciently curved.  Most  persons  become  farsighted  after 
they  pass  the  age  of  forty  years. 

Some  persons  cannot  see  distant  objects  clearly,  but 
have  good  sight  for  objects  which  are  held  only  a  few 
inches  from  their  eyes.  These  persons  are  called  near- 
sighted. The  lenses  of  their  eyes  are  too  curving. 

Sometimes  the  lens  or  the  cornea  is  not  perfectly 
curved,  but  is  irregular  in  shape.  Objects  then  appear 
blurred.  This  trouble  is  called  astigmatism. 

Use  of  Spectacles.  —  Farsightedness,  nearsighted- 
ness,  and  astigmatism  may  all  be  helped  by  the  use 
of  spectacles,  for  the  roundness  of  the  glasses  will  correct 
the  faults  in  the  roundness  of  the  lenses  of  the  eyes. 
Proper  glasses  will  not  harm  the  eyes  in  any  way,  but 
they  will  strengthen  the  eyes,  and  will  keep  the  sight 
from  failing.  Going  without  glasses  when  they  are 
needed  is  often  a  cause  of  weak  eyes  and  headaches. 

Spectacles  that  are  held  in  place  by  bows  over  the 
ears  are  more  comfortable  than  eyeglasses  that  are  held 
in  place  by  springs  fastened  to  the  nose.  If  children 
wear  eyeglasses,  the  pressure  of  the  springs  may  hinder 
the  growth  of  the  bones  of  their  noses. 

No  one  can  see  well  through  dirty  glasses.  If  you 
have  to  wear  glasses,  clean  them  with  a  soft,  clean 
handkerchief  when  they  become  dusty  or  soiled. 

If  the  spectacles  are  set  crooked  on  the  nose,  the 
eyes  will  ache  from  trying  to  look  through  them.  If 
they  will  not  stay  in  place  squarely  in  front  of  the 


350  THE  EYE 

eyes,  bend  their  frames  or  bows  so  that  they  will  fit 
the  eyes. 

Cross-eyed  Sight.  -  -  The  eyeball  may  be  turned 
or  rolled  in  every  direction  by  means  of  six  muscles. 
The  eye  must  be  turned  directly  toward  an  object  in 
order  to  see  it  clearly.  If  a  person's  two  eyes  are  not 
turned  equally  toward  an  object,  two  images  of  the 
object  will  be  seen.  The  person  is  then  said  to  see 
double,  and  to  be  cross-eyed. 

Some  persons  have  double  sight  only  when  their  eyes 
are  tired.  This  is  because  their  muscles  are  able  to 
turn  their  eyes  properly  until  they  become  tired. 
Slight  forms  of  double  sight  are  often  the  cause  of  severe 
headaches.  Cross-eyed  sight  and  the  headaches  re- 
sulting from  it,  may  be  relieved  by  a  good  oculist. 

Signs  of  Poor  Sight.  —  Many  persons  have  poor 
sight  and  do  not  know  it.  Many  children  seem  to  be 
dull  at  school,  because  they  cannot  see  well.  Many 
children  are  born  with  poor  sight,  and  no  one  finds  it 
out  until  the  children  go  to  school. 

One  of  the  principal  signs  of  poor  sight  is  a  headache 
which  comes  on  after  using  the  eyes.  The  cause  of  the 
headache  is  a  pain  in  the  muscles  of  the  eyes. 

Another  sign  of  poor  sight  is  a  blurring  of  the  sight 
after  the  eyes  are  used  for  some  time.  The  cause 
of  the  blurring  is  the  tiredness  of  the  eye  muscles  from 
the  constant  strain  of  focusing  or  turning  the  eyes. 

Testing  the  Sight.  —  Cards  for  testing  the  sight  may 
be  obtained  at  most  jewelry  stores.  They  bear  large 


THE   EYE 


351 


letters  of  various  sizes  clearly  printed  on  cardboard. 
Test  a  person's  eyes  by  placing  one  of  the  cards  about 
twenty  feet  away,  and  have  him  read  as  many  of  the 
letters  as  he  can.  The  following  table  gives  the  dis- 
tances at  which  a  person  with  good  sight  should  be 
able  to  read  letters,  of  various  sizes. 

Height  of  Letter.  Distance  at  which 

it  may  be  Read. 

3^  inches  200  feet 

if  inches  100  feet 

ij  inches  70  feet 

|  inch  50  feet    . 

f  inch  40  feet 

^  inch  30  feet 

f  inch  20  feet 

A  person's  sight  may  be  recorded  in  the  form  of 
a  fraction  in  which  the  numerator  is  the  distance  of 
the  person  from  the  card,  and  "the  denominator  is  the 
distance  at  which  the  smallest  letters  which  he  reads 
should  be  read  by  a  person  with  good  sight.  For  ex- 
ample :  If  a  person  stands  20  feet  from  a  card,  and  the 
smallest  letters  which  he  can  read  are  j-  inch  high,  he 
sees  only  f^,  or  \  as  well  as  a  person  who  has  good 
sight. 

If  your  sight  is  not  good,  go  to  an  oculist  and  let  him 
test  your  sight  and  fit  you  with  glasses.  Most  persons 
who  have  poor  sight  are  able  to  see  well  when  they  wear 
the  right  kind  of  spectacles. 

How  the  Sight  is  Injured.  —  Many  children  are  born 
with  an  eye  weakness  which  becomes  worse  after  strain- 


352  THE  EYE 

ing  the  eyes  and  using  them  improperly.  The  most 
common  causes  of  harming  the  eyes  are  a  wrong  light, 
and  a  wrong  position  in  reading  or  working. 

Wrong  Lighting.  —  A  bright  light  shining  into  the 
eyes  causes  their  muscles  to  contract  so  as  to  shut  out 
the  light.  The  muscles  constantly  pulling  upon  the 
eyeballs  may  press  them  out  of  shape  and  cause  blurred 
sight. 

Reading  in  a  dim  light  tires  the  muscles  of  the  eyes, 
for  when  the  sight  is  not  good,  the  muscles  keep  trying 
to  focus  the  lenses.  A  light  is  of  the  proper  strength 
when  it  is  agreeable  to  your  eyes. 

The  best  position  for  the  light  is  at  your  left  side,  for 
it  then  does  not  shine  into  your  eyes,  and  your  right 
hand  does  not  shade  your  work. 

Improper  Position  in  Reading.  —  When  you  look 
directly  forward,  the  muscles  which  move  your  eyes 
are  at  rest.  When  you  turn  your  eyes  up,  or  down,  or 
sidewise,  the  muscles  flatten  the  eyeball  as  they  pull 
upon  it,  and  prevent  you  from  seeing  distinctly.  When 
you  read,  place  your  book  squarely  in  front  of  your 
face  in  order  that  your  eye  muscles  may  have  as  little 
work  to  do  as  possible.  When  you  study  at  a  table, 
have  the  top  of  your  book  raised,  in  order  that  the 
pages  may  lie  squarely  before  your  eyes  while  you  sit 
upright. 

Reading  while  lying  down  tires  your  eyes,  for  you 
then  have  to  turn  your  eyes  downward  toward  your 
feet.  When  you  read  on  a  railroad  train,  your  book 


THE  EYE  353 

shakes,  and  your  muscles  soon  become  tired  in  keeping 
your  eyes  turned  toward  the  page. 

Injuries  to  the  Eye.  --  The  eye  is  set  deep  in  a  bony 
socket  which  protects  it  from  blows.  It  lies  upon  a  bed 
of  fat  which  acts  like  a  spring  and  allows  it  to  slip  about 
when  it  is  jarred  or  struck.  The  outer  shell  of  the  eye- 
ball is  as  thick  and  tough  as  sole  leather,  and  can 
scarcely  be  cut  with  a  sharp  knife.  An  eye  is  seldom  in- 
jured by  accident  except  by  shot  or  by  sharp  instru- 
ments which  strike  it  directly  in  front. 

Sometimes  the  skin  around  the  eye  is  made  purple 
or  black  by  blows  over  the  eye.  The  color  is  seldom  in 
the  eye  itself,  but  is  in  the  bruised  skin  around  the  eye. 

Dirt  in  the  Eye.  --  The  eye  is  covered  with  two  mov- 
able lids  which  protect  it  from  dust  and  slight  injuries. 
The  surface  of  the  eye  is  moistened  with  a  fluid,  called 
tears,  which  is  produced  by  a  gland  lying  just  above 
the  eyeball. 

The  eye  is  very  tender,  and  becomes  painful  when 
there  is  a  speck  of  hard  dirt  between  the  lids  and  the 
eyeball.  If  you  have  a  bit  of  dirt  under  an  eyelid,  do 
not  rub  the  eye,  for  the  rubbing  makes  the  dirt  scratch 
the  eye.  Grasp  the  eyelashes,  and  hold  the  lid  away 
from  your  eyeball  for  a  moment.  The  tears  may  then 
wash  the  dirt  away.  If  the  dirt  does  not  come  away, 
let  a  friend  lift  the  eyelid  and  brush  the  dirt  away  with 
the  corner  of  a  clean  handkerchief. 

Sore  Eyes.  — The  most  common  cause  of  sore  eyes 
is  disease  germs  growing  under  the  eyelids  and  on  the 

GEN.   HYG. 23 


354  THE  EYE 

eyeball.  The  germs  make  the  eyes  red,  and  cause 
them  to  smart  and  to  ache.  Many  kinds  of  eye  diseases 
are  infectious,  and  are  caught  from  other  persons  who 
have  sore  eyes. 

Do  not  use  a  towel  or  handkerchief  which  has  been 
soiled  by  any  one  with  sore  eyes.  If  you  have  sore 
eyes,  use  your  own  towels  and  handkerchiefs,  and  boil 
them  before  they  are  washed.  You  can  help  to  cure 
sore  eyes  by  washing  them  often  with  warm  water  so 
as'  to  remove  the  germs. 

The  eyes  of  babies  are  often  injured  by  allowing 
house  flies  to  crawl  over  them.  When  a  baby  is  asleep, 
drive  the  flies  from  the  room,  or  cover  its  face  with 
mosquito  netting  in  order  to  prevent  flies  from  crawling 
over  its  face. 

One  form  of  sore  eyes  is  called  granulated  lids,  or 
trachoma.  It  is  very  infectious,  and  is  becoming  com- 
mon in  some  places.  If  it  is  not  properly  treated,  it 
becomes  worse  and  worse,  and  often  destroys  the  sight. 
But  it  may  readily  be  cured  by  a  doctor. 

Training  the  Eye.  —  When  you  look  at  an  object, 
images  of  everything  in  front  of  your  eyes  are  formed 
on  their  retinas,  but  the  brain  takes  notice  of  only  the 
images  which  you  wish  to  see.  For  example,  if  you 
look  at  a  bird  in  a  tree,  images  of  the  bird,  the  tree, 
and  the  sky  are  all  formed  in  your  eyes,  but  your  brain 
takes  notice  of  the  image  of  the  bird  only. 

When  you  look  carefully  at  an  object,  the  thing  which 
you  wish  to  see  is  often  the  dimmest  and  most  blurred 


THE  EYE  355 

part  of  the  object.  You  can  train  your  brain  to 
notice  and  recognize  dim  and  blurred  images  that 
scarcely  make  an  impression  on  the  eye  at  all.  For 
example,  a  sailor,  seeing  a  dim  speck  miles  away  on 
the  water,  can  tell  whether  or  not  it  is  a  ship,  and  what 
kind  of  vessel  it  is.  Training  the  eyes  is  really  brain 
training.  Any  person  who  has  fair  sight  can  train  his 
brain  to  see  things  which  an  untrained  brain  will  not 
notice  at  all. 

Tobacco  and  the  Eyes.  —  Tobacco  sometimes  in- 
jures the  nerve  of  the  eye,  and  produces  blindness. 
Smoking  is  more  likely  to  injure  the  eyes  than  the  use 
of  tobacco  in  any  other  form.  The  blindness  usually 
passes  off  when  the  tobacco  is  stopped. 

QUESTIONS 

Describe  the  eyeball,  and  name  its  principal  parts. 
Of  what  use  is  the  iris  ? 
Of  what  use  is  the  lens  ? 

In  what  respect  is  the  eye  like  a  photographer's  camera  ? 
How  is  the  eye  focused  ? 
What  is  farsightedness  ? 
What  is  nearsightedness? 
,  What  is  astigmatism? 
How  do  spectacles  help  the  sight  ? 

Why  are  spectacles  with  bows  more  healthful  than  eye- 
glasses that  pinch  the  nose  ? 

What  is  the  cause  of  double  sight  ? 
What  are  some  of  the  signs  of  poor  sight  ? 
How  does  poor  sight  cause  a  headache  ? 


356  THE  EYE 

How  can  you  test  the  sight  ? 

How  does  a  wrong  light  injure  the  eyes  ? 

How  does  reading  on  a  railroad  train  tire  the  eyes  ? 

What  position  of  the  body  and  arrangement  of  the  light  are 
the  most  comfortable  for  the  eyes  ? 

How  is  the  eye  protected  from  injury  ? 

Of  what  use  are  tears  ? 

Why  is  it  harmful  to  rub  an  eye  when  there  is  a  speck  of  dirt 
in  it? 

How  can  you  remove  dirt  from  under  an  eyelid  ? 

Name  some  ways  in  which  soreness  of  the  eyes  may  be  spread 
from  one  person  to  another. 

What  is  trachoma? 

How  can  you  train  your  eyes  to  see  faint  and  indistinct 
objects  ? 

What  effect  does  tobacco  have  upon  the  sight  ? 


CHAPTER  XXXIII 
THE  VOICE 

Vocal  Cords.  -  -  The  sound  of  the  voice  is  made  in  a 
box,  called  the  larynx,  which  forms  the  uppermost 
part  of  the  windpipe.  The  front  upper  corner  of  this 


Diagram  of  the  vocal  cords,    a,  epiglottis;  b,  vocal  cords. 

box  forms  the  lump  called  the  Adam's  Apple,  that  may 
be  felt  in  the  front  of  the  neck  just  below  the  chin. 

Two  white  bands  of  flesh  called  vocal  cords  are 
tightly  stretched  backward  across  the  top  of  the  larynx. 
When  the  cords  are  tightened  and  brought  close 
together,  and  air  is  forced  between  them,  they  tremble 
back  and  forth  and  make  a  sound  in  the  same  way 
that  blowing  through  a  tin  horn  produces  a  noise. 
The  sound  made  by  the  vocal  cords  alone  is  unpleas- 
ant and  squeaking,  but  it  is  increased  in  power  and 
made  pleasant  by  means  of  the  nose,  mouth,  tongue, 
and  teeth. 

357 


358  THE   VOICE 

Speech.  —  When  a  sound  is  made  in  the  throat,  the 
lips,  teeth,  and  tongue  may  change  the  air  current  in 
such  a  way  that  the  sound  forms  letters  and  words. 
You  form  the  letter  P  by  starting  with  your  lips  closed, 
and  suddenly  forcing  them  open  with  a  blast  of  air 
which  passes  through  the  vocal  cords.  You  form  the 
letter  M  by  starting  a  sound  with  the  lips  open,  and 
suddenly  closing  them.  When  you  whisper,  you  do  not 
use  the  vocal  cords  at  all,  but  make  use  of  the  sound 
produced  by  blowing  air  through  the  lips. 

Some  boys  and  girls  who  do  not  pronounce  their 
words  plainly  suppose  there  is  something  wrong  with 
their  lips  or  tongue.  This  is  almost  never  so.  The 
reason  why  they  do  not  talk  distinctly  is  because  they 
have  not  learned  to  move  their  lips  and  tongue  cor- 
rectly. They  can  learn  to  speak  distinctly  if  they  will 
notice  the  correct  positions  of  the  tongue  and  lips  in 
pronouncing  difficult  words,  and  will  then  practice 
speaking  the  words  clearly. 

Hearing  and  Speech.  —  A  person  who  cannot  talk 
is  said  to  be  dumb.  A  baby  learns  to  talk  by  hearing 
the  voices  of  other  persons.  The  reason  why  dumb 
persons  cannot  talk  is  that  they  are  deaf  and  do  not 
know  what  words  sound  like.  There  is  seldom  any- 
thing the  matter  with  their  noses  and  throats,  and 
they  learn  to  talk  when  they  are  shown  how  to  place 
their  lips  and  tongues  in  order  to  form  words.  Children 
who  are  totally  deaf  soon  learn  to  talk  when  they  are 
sent  to  a  school  for  the  deaf  and  dumb. 


THE  VOICE  359 

A  Pleasing  Tone  of  Voice.  — You  like 'to  hear  some 
persons  talk,  because  their  words  sound  like  music. 
The  voices  of  others  are  loud,  or  shrill,  or  whining,  or 
have  some  other  unpleasant  tone  that  makes  you  feel 
uncomfortable.  A  voice  with  an  unpleasant  tone 
keeps  you  from  resting  and  increases  your  discomfort 
when  you  are  sick.  The  tone  of  voice  with  which  you 
usually  speak  will  have  a  great  effect  upon  the  health 
and  comfort  of  others. 

You  can  form  a  habit  of  speaking  with  a  pleasing 
tone  if  you  try  to  do  so.  To  speak  always  in  a  pleasant 
and  distinct  tone  of  voice  is  one  of  the  most  pleasing 
habits  that  you  can  form. 

Exercising  the  Voice.  -  -  The  sound  of  the  voice  is 
formed  by  means  of  muscles.  If  boys  and  girls  do  not 
use  their  voice  muscles,  they  will  grow  up  with  weak 
voices,  and  will  be  unable  to  sing  or  speak  with  strong 
voices,  or  for  many  minutes  at  a  time. 

You  can  make  your  voice  muscles  strong  by  exer- 
cising them,  just,  as  you  make  the  muscles  of  your  arm 
strong  by  use.  A  good  form  of  voice  exercise  is  to 
read  aloud  at  home  in  the  evening. 

If  you  use  your  voice  muscles  until  they  are  overtired, 
you  will  make  them  weak,  just  as  overworking  your 
arm  muscles  will  make  them  weak.  Some  of  the  ways 
in  which  boys  and  girls  are  likely  to  injure  their  voice 
muscles  is  by  loud  shouting,  singing  for  $.  long  time, 
and  cheering  at  games. 

The  voice  of  a  young  boy  sounds  like  a  girl's  voice, 


360  THE   VOICE 

but  at  about  the  age  of  fifteen  his  larynx  suddenly 
grows  faster  than  his  body.  This  growth  produces  a 
change  in  his  voice  by  which  it  becomes  low-pitched 
and  deep  like  a  man's  voice.  While  this  change  is 
taking  place,  the  voice  muscles  may  be  strained  more 
easily  than  at  any  other  time. 


QUESTIONS 

Where  is  the  sound  of  the  voice  made  ? 

Describe  the  larynx. 

How  do  the  vocal  cords  produce  sound  ? 

What  organs  do  you  use  when  you  pronounce  letters  and 
words  ? 

How  do  you  form  the  letter  P  ? 

How  is  the  letter  M  formed  ? 

How  can  you  improve  the  distinctness  of  your  speech  ? 

What  is  the  cause  of  dumbness  ? 

How  may  a  deaf  and  dumb  person  be  taught  to  speak  ? 

Name  some  ways  in  which  the  tone  of  the  voice  may  affect 
a  person's  health. 

How  can  you  exercise  the  voice  ? 

Name  some  ways  in  which  the  voice  may  be  strained. 

What  is  the  change  of  voice  in  boys  ? 


CHAPTER  XXXIV 
PUBLIC  HEALTH  AGENCIES 

Schools.  —  Men  of  olden  times  lived  in  a  natural 
way  like  wild  animals,  and  were  as  healthy  as  the  wild 
animals.  When  men  began  to  build  houses  and  to 
live  in  cities,  they  shut  out  the  life-giving  light  and  air, 
and  polluted  their  supplies  of  food  and  water.  They 
then  began  to  suffer  from  epidemics  and  pestilences 
that  were  almost  unknown  while  they  lived  in  a  wild 
state.  One  object  of  teaching  hygiene  in  schools  is 
to  teach  pupils  how  they  can  live  in  modern  houses 
and  in  crowded  cities  and  still  preserve  all  that  was 
healthful  in  the  natural  way  of  living  as  wild  animals 
live.  It  is  the  duty  of  the  government  to  compel  each 
child  to  learn  how  to  live  a  healthful  life. 

Street  Cleaning.  -  -  The  streets  of  a  town  or  city 
belong  to  the  people,  and  are  free  for  everybody  to  use. 
It  is  the  duty  of  the  government  to  keep  them  clean 
and  safe  for  those  who  use  them.  The  work  of  a 
street  cleaning  department  of  a  city  has  an  important 
effect  on  the  health  of  the  people  of  the  city. 

The  dust,  and  dirt  of  city  streets  usually  contain 
disease  germs  which  come  from  sick  persons  and  sick 
animals.  There  is  often^a  great  increase  in  the  number 

361 


362  PUBLIC   HEALTH   AGENCIES 

of  persons  sick  with  colds  and  sore  throats  in  the  spring 
when  warm  weather  sets  free  the  disease  germs  which 
snow  and  ice  have  bound  fast  to  the  streets  during  the 
winter.  One  of  the  duties  of  the  street  cleaning  depart- 
ment of  a  city  is  to  sweep  and  clean  the  streets.  The 
department  also  clears  away  the  snow  and  ice,  and 
makes  paths  through  the  snowy  streets.  It  also 
sprinkles  the  streets  on  dry  days  in  order  to  prevent 
dust  and  disease  germs  from  blowing  into  the  faces 
and  homes  of  the  people.  New  York  employs  about 
3000  street  cleaners  who  clean  about  1500  miles  of 
street  every  day. 

City  Rubbish.  --The  people  of  cities  have  no  large 
back  yards  or  waste  lands  on  which  they  can  dump 
their  ashes  and  rubbish.  If  house  wastes  are  left  in 
piles,  they  decay  and  become  the  breeding  places  for 
disease  germs,  flies,  and  rats.  The  street  cleaning 
department  collects  the  waste  rubbish  and  garbage, 
and  carts  them  away.  This  is  expensive,  but  many 
cities  sort  over  the  rubbish  and  make  use  of  a  large 
part  of  it.  Ashes  are  used  to  fill  in  low  land.  Papers 
and  everything  else  that  will  burn  are  fed  to  the  boilers 
of  steam  engines.  Rags  are  sold  for  paper  making, 
bones  for  fertilizer,  and  tin  cans  for  solder.  Waste 
meat  and  table  leavings  are  boiled  and  pressed  in  order 
to  extract  their  fat,  and  the  refuse  is  sold  for  fertilizer. 
About  1500  drivers  of  rubbish  carts  are  employed  by 
the  street  cleaning  department  of  New  York. 

Water  Supply.  —  Every  person  in  a  city  must  use 


PUBLIC   HEALTH   AGENCIES  363 

water,  but  it  is  often  impossible  to  obtain  an  abundant 
supply  of  pure  water  without  going  a  long  distance 
away.  It  is  the  duty  of  every  city  government  to 
provide  pure  water  for  every  person  in  the  city.  Most 
cities  build  waterworks  at  public  expense,  and  sell  the 
water  to  the  people  at  low  rates. 

Sewage  Disposal.  -  -  The  work  of  the  water  depart- 
ment of  a  city  is  only  half  done  when  it  has  brought 
pure  water  into  a  town,  for  the  used-up  water  is  dirty 
and  impure,  and  full  of  disease  germs,  and  must  be 
removed.  It  is  proper  for  the  government  to  remove 
sewage  at  public  expense,  for  every  person  helps  to 
make  the  waste  water  impure  and  dangerous  to  health. 

The  old-fashioned  way  of  getting  rid  of  sewage  was 
to  empty  it  into  the  nearest  stream  or  body  of  water. 
This  method  endangers  the  health  of  other  people 
who  use  the  water  in  any  way.  It  is  the  duty  of  every 
city  to  erect  a  sewage  disposal  plant,  in  order  that  its 
sewage  will  not  make  the  people  of  other  places  sick 
(p.  179). 

Fire  Department.  —  Fires  are  the  cause  of  hundreds 
of  deaths  each  year.  They  destroy  millions  of  dollars' 
worth  of  property,  and  produce  untold  suffering.  They 
often  endanger  the  safety  of  a  whole  city.  A  fire  depart- 
ment is  a  necessity  in  every  town  and  city.  Firemen 
often  have  to  go  into  places  which  are  far  more  danger- 
ous than  a  field  of  battle,  and  every  day  they  do  deeds 
which  are  as  heroic  as  any  which  a  soldier  has  to  per- 
form. 


364 


PUBLIC   HEALTH  AGENCIES 


The  duty  of  a  fire  department  is  to  prevent  fires  as 
well  as  to  put  them  out  after  they  have  started.  Most 
cities  have  laws  against  storing  rubbish  in  cellars  and 
back  yards  where  there  is  danger  of  fires  spreading. 

There  are  also  laws 
against  storing 
gasoline,  gun- 
powder, and  other 
explosives  in  build- 
ings where  people 
live  and  work,  and 
against  starting 
fires  and  burning 


A  hose  cart  going  to  a  fire  in  New  York. 


rubbish  near  build- 
ings. It  is  the 
duty  of  the  officers  of  the  fire  department  to  enforce 
the  fire  laws.  They  also  see  that  the  aisles  of  public 
meeting  places  are  not  obstructed,  and  that  fire  es- 
capes are  in  good  order  and  ready  for  instant  use. 

Carelessness  with  Matches.  —  More  fires  are  due  to 
carelessness  in  handling  matches  than  to  any  other 
cause.  Smokers  often  carry  matches  loose  in  their 
pockets,  and  throw  burning  matches  and  cigar  ends 
on  the  floor  and  into  waste  baskets.  Boys  and  girls 
often  start  fires  by  playing  with  matches.  There 
are  about  five  times  as  many  fires  in  the  United  States 
as  in  Germany.  The  principal  reason  why  this  is  so  is 
because  the  people  of  Germany  are  more  careful  with 
matches  and  fire  than  the  people  of  the  United  States. 


PUBLIC   HEALTH  AGENCIES  365 

Parks  and  Playgrounds.  —  Boys  and  girls  cannot 
be  healthy  and  happy  without  play.  In  crowded 
cities  there  are  /ew  places  in  which  to  play  out  of  doors, 
except  in  the  streets.  It  is  the  duty  of  the  government 
to  provide  open  parks  and  playgrounds  where  children 
may  run  and  play  games  away  from  the  dust,  disease 
germs,  and  other  dangers  of  the  streets. 

Playgrounds  improve  the  behavior  of  boys  and  girls 
as  well  as  their  health.  Whenever  a  new  playground 
is  opened  in  New  York  there  is  always  a  lessening  in 
the  amount  of  mischief  and  crime  among  the  boys 
who  live  near  it,  for  they  expend  their  strength  in  play 
instead  of  in  troubling  other  people. 

Hospitals.  —  Every  city  and  village  has  many  poor 
people  who  have  no  place  where  they  can  receive  proper 
care  when  they  are  sick.  Many  people,  both  rich  and 
poor,  have  no  houses  or  rooms  in  which  they  may  have 
surgical  operations  performed,  or  in  which  they  may 
be  isolated  or  quarantined  when  they  have  contagious 
diseases.  Public  hospitals  are  provided  where  they 
can  receive  doctoring  and  nursing  and  be  restored  to 
health  and  strength.  New  York  has  over  a  hundred 
public  hospitals  where  the  poor  may  stay  and  be 
treated.  There  are  also  about  sixty-five  public  dis- 
pensaries for  the  treatment  of  poor  people  who  are  able 
to  walk  about. 

Tuberculosis  Hospitals.  —  More  people  are  sick 
with  tuberculosis  than  with  any  other  disease,  but 
there  are  fewer  hospitals  for  the  treatment  of  tuberculo- 


366  PUBLIC   HEALTH  AGENCIES 

sis  than  for  the  treatment  of  other  diseases.  The  pre- 
vention and  treatment  of  tuberculosis  consist  largely 
in  educating  the  sick  persons  themselves  in  the  way  to 
eat,  to  breathe,  to  sleep,  and  to  dispose  of  their  sputum. 
This  may  best  be  done  in  a  hospital  for  tuberculosis 
cases  only.  When  the  governments  of  cities,  counties, 
and  states  erect  enough  hospitals  for  the  treatment  of 
those  who  have  tuberculosis,  and  also  compel  all  those 
who  have  tuberculosis  to  learn  how  to  prevent  its 
spread  to  others,  the  disease  may  be  wiped  out  as 
completely  as  smallpox  has  been. 

Churches.  —  In  olden  times  the  priests  of  the 
churches  and  temples  were  almost  the  only  teachers  of 
the  young,  and  healers  of  the  sick.  One  great  work  of 
the  church  is  still  to  assist  in  the  education  of  the  young, 
to  comfort  the  sick,  and  to  promote  healthfulness 
among  all  people.  Churches  are  found  in  every  city 
and  village.  They  assist  the  poor  and  the  needy,  and 
are  among  the  greatest  of  all  institutions  for  promoting 
the  health  and  peace  of  the  country. 

Charitable  Societies.  —  Many  helpless  children  and 
unfortunate  old  persons  need  help  in  every  town  and 
city.  The  government  provides  homes  for  orphans, 
for  aged  people,  and  for  the  insane.  There  are  also 
a  great  number  of  societies  for  the  help  of  the  needy, 
such  as  societies  for  the  prevention  of  cruelty  to  chil- 
dren, for  teaching  the  blind,  for  promoting  temperance, 
and  for  the  help  of  crippled  children.  These  societies 
do  an  immense  amount  of  good  in  promoting  health. 


PUBLIC   HEALTH  AGENCIES  367 

Health  of  Mind  and  Body.  —  Men  of  olden  times 
thought  that  the  body  was  opposed  to  the  mind.  They 
used  to  starve  themselves,  and  to  torture  their  flesh  in 
trying  to  weaken  their  bodies  so  as  to  free  their  minds 
and  spirits.  Now  we  know  that  the  only  persons 
whose  minds  are  entirely  free  are  those  whose  bodies 
are  in  such  perfect  health  that  their  minds  are  not 
disturbed  by  any  unpleasant  bodily  feelings.  The 
first  thing  to  do  in  helping  the  mind  of  any  troubled 
person  is  to  help  him  to  make  his  body  comfortable 
and  healthy.  One  of  the  greatest  of  all  the  duties  of 
a  government  is  to  provide  the  means  by  which  each 
person  may  preserve  a  healthy  mind  in  a  healthy 
body. 

QUESTIONS 

Give  some  reasons  why  the  government  should  compel  every 
school  child  to  study  hygiene. 

Give  some  reasons  why  officers  of  a  city  should  sprinkle  and 
clean  the  streets  at  public  expense. 

Give  some  reasons  why  the  city  should  remove  garbage  and 
rubbish  at  public  expense. 

Why  should  the  water  supply  of  a  town  be  under  the  control 
of  the  government  ? 

Why  should  the  sewage  disposal  of  a  town  be  at  public 
expense  ? 

How  does  the  fire  department  help  to  promote  the  health  of 
a  town  ? 

Of  what  use  are  parks  and  playgrounds  in  promoting  the 
health  of  the  people  of  a  town  ? 


368  PUBLIC   HEALTH  AGENCIES 

Give  some  reasons  why  the  government  should  build  hos- 
pitals for  the  treatment  of  tuberculosis. 

How  do  churches  promote  good  health  among  people? 

How  do  charitable  societies  promote  good  health  ? 

How  does  good  bodily  health  promote  good  health  of  the 
mind? 


GLOSSARY 

Absorbent  cotton,  cotton  prepared  for  dressing  wounds. 
Absorption,  taking  food  from  the  intestine  by  the  blood. 
Acetic  acid,  the  sour  substance  in  vinegar. 
Adenoids,  soft  growths  of  flesh  in  the  back  part  of  the  throat 

and  behind  the  nose. 
Adulteration,  mixing  a  cheap  substance  with  a  valuable  one  in 

order  that  the  mixture  may  closely  imitate  the  valuable 

substance. 

Albumin,  another  name  for  protein. 
Alcohol,  a  colorless  liquid  used  in  manufacturing.     It  is  also 

found  in  beer,  wine,  whisky,  and  other  strong  drinks. 
Alga,  one  of  the  simplest  kinds  of  plants. 
Anatomy,  the  study  of  the  structure  of  the  body. 
Antiseptic,  a  substance  that  will  kill  bacteria  and  disease  germs. 
Antitoxin,  a  substance  that  will  destroy  the  poisons  of  disease 

germs  in  the  body.     Antitoxins  for  diphtheria  and  lock- 
jaw are  in  common  use. 
Aorta,  the  artery  next  to  the  heart. 
Artery,  a  blood  tube  that  carries  blood  from  the  heart. 
Artificial  respiration,  making  air  pass  into  and  out  of  the  lungs 

in  imitation  of  natural  breathing. 
Assimilation,  making  food  into  a  part  of  the  body,  or  putting 

food  to  use  in  the  body. 

Astigmatism,  blurred  sight  due  to  an  unevenness  of  the  cornea. 
Auricles,  the  two  thin-walled  cavities  on  the  upper  end  of  the 

heart. 
Bacteria,  the  smallest  known  plants.     Some  cause  decay,  and 

others  produce  diseases. 

GEN.   HYG. 24  369 


370  GLOSSARY 

Bandage,  a  dressing  wrapped  around  a  wounded  part. 

Biceps,  the  muscle  that  bends  the  elbow. 

Board  of  Health,  a  body  of  officers  who  have  charge  of  matters 

pertaining  to  public  health. 
Bronchi,  the  air  tubes  of  the  lungs. 
Caffeine,  the  stimulating  substance  in  coffee  and  tea. 
Calorie,  the  quantity  of  heat  that  will  raise  the  temperature  of 

four  pounds  of  water  very  nearly  one  degree  Fahrenheit. 
Capillaries,  the  microscopic  blood  tubes  that  connect  the  arteries 

and  the  veins. 

Carbohydrates,  starches  and  sugars. 

Carbolic  acid,  a  poisonous  liquid  used  to  kill  disease  germs. 
Carbon,  a  substance  found  in  every  living  thing ;   charcoal. 
Carbon  dioxide,  a  gas  formed  by  burning  or  oxidizing  carbon. 
Cartilage,  tough  flesh  resembling  softened  bone ;   gristle. 
Catarrh,  a  kind  of  throat  trouble  that  resembles  a  constant  cold. 

It  is  usually  caused  by  adenoids. 
Cells,  the  smallest  bits  of  living  matter  that  are  capable  of 

growing  when  separated  from  the  body. 
Cerebellum,  the  rounded  part  of  the  brain  under  the  hinder 

part  of  the  cerebrum. 
Cerebrum,  the  large  rounded  mass  forming  the  upper  part  of 

the  brain. 
Certified  milk,  pure,  clean  milk  produced  under  the  oversight 

of  a  board  of  doctors. 

Cesspool,  an  underground  tank  for  receiving  sewage. 
Choroid  coat,  the  dark  coat  on  the  inside  of  the  eyeball. 
Cilia,  the  velvet-like  projections  on  the  lining  of  the  bronchi. 
Circulation,  the  flow  of  blood  through  the  body. 
Coagulation,    the    process    of    a    liquid    becoming   jelly-like; 

clotting. 

Cold,  any  mild  form  of  infectious  disease. 
Cold  storage,  preserving  articles  in  rooms  which  are  kept  nearly 

freezing  cold. 


GLOSSARY  371 

Congest,  to  fill  with  more  blood  than  usual. 

Connective  tissue,  the  tough  fibers  that  hold  cells  in  place. 

Consumption,  a  lung  disease  caused  by  the  bacteria  of  tuber- 
culosis. 

Convulsion,  a  contraction*  of  all  of  the  muscles  of  the  body,  due 
to  sickness-! 

Cornea,  the  clear  window  in  the  front  of  the  eyeball. 

Corpuscles,  the  bodies  that  float  in  the  liquid  part  of  the  blood. 

Culture,  an  artificial  growth  of  bacteria  in  a  bottle  or  tube. 
Cultures  are  usually  made  to  determine  their  kinds. 

Decay,  the  process  by  which  matter  once  living  slowly  goes  to 
pieces  and  is  finally  returned  to  the  soil  and  air. 

Diaphragm,  the  sheet  of  muscle  extending  across  the  body  near 
the  waistline. 

Digestion,  dissolving  food  to  forms  that  may  enter  the  blood. 

Diphtheria,  a  throat  disease  caused  by  the  growth  of  diphtheria 
bacteria. 

Disinfectant,  a  substance  that  will  kill  disease  germs. 

Dislocate,  to  slip  the  ends  of  two  bones  of  a  joint  past  each  other ; 
to  put  out  of  joint. 

Distillation,  separating  alcohol  from  a  boiling  liquid  by  collect- 
ing the  steam  and  cooling  it. 

Emulsion,  a  milky  liquid  in  which  small  drops  of  fat  float  in 
water. 

Enamel,  the  hard  coating  on  the  outside  of  a  tooth. 

Epidemic,  a  disease  that  attacks  a  large  number  of  people  at 
once. 

Epidermis,  the  thin,  outer  covering  of  the  skin  ;  epithelium. 

Epiglottis,  the  lid  at  the  upper  end  of  the  windpipe. 

Epilepsy,  convulsions  due  to  a  brain  disease. 

Epithelium,  the  cells  forming  the  outer  coating  of  the  skin,  and 
the  lining  of  the  air  tubes  and  digestive  organs. 

Esophagus,  the  tube  that  conducts  food  from  the  throat  to  the 
stomach. 


372  GLOSSARY 

Eustachian  tube,  the  air  tube  leading  from  the  throat  to  the 

middle  ear. 
Excretions,  the  oxidized  substances  and  waste  matters  of  the 

body. 
Fermentation,  changing  a  liquid  containing  sugar  to  carbon 

dioxide  and  alcohol. 

Filter,  a  tank  of  sand  used  for  removing  impurities  from  water. 
Focusing,  changing  the  shape  of  the  lens  of  the  eye  in  order  to 

see  clearly. 
Formalin,  a  colorless  liquid  used  for  killing  bacteria  and  disease 

germs. 

Fumigation,  destroying  disease  germs  by  means  of  a  gas. 
Funny  bone,  the  nerve  on  the  inner  side  of  the  tip  of  the  elbow. 
Ganglia,  collections  of  nerve  cells  in  the  sympathetic  nervous 

system. 
Garbage,  waste  food  and  other  substances  thrown  away  from 

the  kitchen. 
Gas  trap,  a  portion  of  a  waste  pipe  bent  sharply  in  order  to  hold 

water  and  prevent  sewer  gas  from  flowing  through  the 

pipe. 

Gastric  juice,  the  liquid  produced  by  the  stomach  to  digest  food. 
Gland,  a  collection  of  tubes  that  remove  substances  from  the 

blood. 

Hemoglobin,  the  red  coloring  matter  of  the  blood. 
Humerus,  the  bone  in  the  upper  half  of  the  arm. 
Hydrogen,  a  substance  that  forms  a  part  of  every  living  thing. 

Pure  hydrogen  is  a  gas,  and  forms  water  when  it  is  burned. 
Hydrophobia,  a  disease  of  the  brain  usually  caught  from  mad 

dogs ;   rabies. 

Hygiene,  the  study  of  the  care  of  the  body. 
Hysterics,  a  mental  sickness  with  great  laughing  or  crying. 
Idiot,  a  grown  person  who  has  the  mind  of  a  baby. 
Immunity,  the  ability  of  the  body  to  prevent  the  growth  of 

disease  germs  in  the  flesh  or  blood. 


GLOSSARY  373 

Infection,  taking  germs  of  a  disease  into  the  body. 

Infectious  diseases,  forms  of  sickness  due  to  the  growth  of 
disease  germs  in  the  flesh  or  blood. 

Insanity,  any  mental  disease  in  which  the  sick  person  is  con- 
tinuously unable  to  think  naturally. 

Intemperance,  satisfying  a  false  appetite. 

Intoxication,  a  poisoning  by  alcohol. 

Iris,  the  colored  curtain  in  the  front  part  of  the  eyeball. 

Lacteals,  the  lymph  tubes  that  take  digested  fat  from  the  in- 
testine. 

Lactic  acid,  the  sour  substance  in  sour  milk. 

Larynx,  the  box  of  cartilage  in  which  the  sound  of  the  voice  is 
formed. 

Lens,  the  part  of  the  eyeball  that  forms  clear  images  in  the  eye. 

Ligaments,  the  tough  bands  of  flesh  that  bind  the  bones  of  a 
joint  together. 

Liver,  the  gland  that  manufactures  bile. 

Lymph,  the  liquid  that  passes  from  the  blood  through  the  sides 
of  the  capillaries  to -feed  the  cells  of  the  body. 

Lymphatics,  the  fine  tubes  that  conduct  lymph  toward  the 
heart. 

Maggot,  a  young  fly  in  its  worm-like  stage. 

Malt,  sprouted  grain  used  in  making  beer. 

Medulla,  the  part  of  the  brain  next  to  the  spinal  cord. 

Microbes,  bacteria. 

Minerals,  the  part  of  the  body  that  is  left  as  ashes  when  the 
body  is  burned. 

Molars,  the  double  teeth. 

Mold,  microscopic  thread-like  plants  that  grow  on  damp  places 
and  often  produce  a  velvet-like  covering  on  food  and 
clothing. 

Morphine,  the  narcotic  poison  in  opium. 

Motor  nerves,  nerves  that  carry  messages  away  from  the  brain 
or  spinal  cord. 


374  GLOSSARY 

Mucous  membrane,  the  skin-like  lining  of  the  air  passages  and 

digestive  tube. 
Mucus,  the  substance,  like  white  of  egg,  formed  by  mucous 

membranes. 
Muscle,  a  bundle  of  cells  that  produce  a  motion  of  some  part 

of  the  body ;   lean  meat. 

Narcotic,  a  substance  that  dulls  the  mind  and  produces  sleep. 
Nerve,  a  thread  or  string  of  flesh  that  carries^messages  between 

the  brain  or  the  spinal  cord  and  another  part  of  the  body. 
Nicotine,  the  principal  poisonous  substance  in  tobacco. 
Nitrogen,  the  gas  that  forms  four  fifths  of  the  air. 
Nucleus,  the  dark-colored  spot  seen  in  most  cells. 
Opium,  the  dried  juice  of  a  poppy  plant.     It  is  a  narcotic,  and 

produces  sleep. 

Organ,  a  part  of  the  body  having  a  definite  work  to  do. 
Osmosis,  the  mixing  of  two  liquids  or  gases  when  separated  by 

a  thin  sheet  or  membrane. 

Oxidation,  the  union  of  oxygen  with  a  substance ;  burning. 
Oxygen,  a  gas  that  forms  one  fifth  of  the  air.     It  supports 

oxidation  and  is  the  substance  taken  from  the  air  by 

the  act  of  breathing. 

Pancreas,  a  gland  that  produces  one  of  the  digestive  juices. 
Pancreatic  juice,  the  digestive  liquid  formed  by  the  pancreas. 
Panic,  a  fear  that  leads  a  crowd  to  act  in  a  dangerous  manner. 
Papillae,  the   tiny  projections  that  form  lines  and  patterns  on 

the  skin,  especially  on  the  palms  of  the  hands. 
Paralyzed,  unable  to  move  a  part  of  the  body. 
Paramecium,  a  microscopic  animal  composed  of  a  single  cell. 
Pasteurize,  killing  bacteria  in  a  substance  by  a  heat  just  below 

boiling. 

Peptone,  digested  protein. 
Periosteum,  the  skin-like  covering  of  a  bone. 
Peristalsis,  the  motions  of  the.  digestive  organs  by  which  food 

is  forced  down  them. 


GLOSSARY  375 

Perspiration,  sweat. 

Pharynx,  the  muscular  bag  forming  the  back  part  of  the  throat. 

Physiology,  the  study  of  the  work  of  the  body. 

Plague,  a  dangerous  disease  that  is  spread  mostly  by  rat  fleas. 

Plasma,  the  liquid  part  of  the  blood ;   serum. 

Pores,  the  openings  of  the  sweat  glands. 

Protein,  the  substance,  like  white  of  egg,  that  forms  the  living 

part  of  every  plant  and  animal. 

Ptomaine  (to'ma-in),  a  poison  formed  by  the  decay  of  a  sub- 
stance. * 

Pupil,  the  round  hole  in  the  iris  admitting  light  into  the  eye. 
Pus,  the   creamy  matter  flowing  from  a  wound.     It  consists 

mainly  of  white  blood  cells  killed  by  disease  germs. 
Quarantine,  preventing  the  spread  of  an  infectious  disease  by 

keeping  the  sick  away  from  the  well. 
Rabies,  hydrophobia. 

Radius,  the  bone  on  the  thumb  side  of  the  arm  below  the  elbow. 
Reflex  action,  the  action  of  the  brain  or  spinal  cord  made  in 

response  to  a  sensory  message. 

Reservoir,  a  very  large  tank  in  which  water  is  stored. 
Respiration,  breathing  and  the  oxidation  in  the  body. 
Retina,  the  inner  coating  of  the  eyeball.     It  contains  the  nerves 

of  sight. 

Saliva,  the  digestive  fluid  in  the  mouth. 
Sanatorium,  a  home  in  which  unhealthy  persons  are  taught 

how  to  live  healthful  lives. 
Scarlet  fever,  an  infectious  fever  in  which  there  is  redness  of 

the  skin,  followed  by  a  peeling  of  the  epidermis. 
Scrofula,  enlarged  glands  in  the  neck. 
Sebaceous  gland,  a  gland  which  produces  oil  to  soften  the  skin 

and  hair. 

Secretion,  the  substance  formed  by  a  gland. 
Sensory  nerves,  the  nerves  that  carry  messages  to  the  spinal 

cord  or  brain. 


376  GLOSSARY 

Septic  tank,  a  tank  in  which  the  solid  matters  of  sewage  decay 
and  are  liquefied. 

Serum,  the  liquid  part  of  blood. 

Sewage,  waste  water  from  houses  and  barns. 

Shock,  sudden  weakness  or  sickness  due  to  an  injury. 

Skeleton,  a  complete  set  of  bones  of  the  body. 

Spinal  cord,  the  part  of  the  nervous  system  that  is  contained 
inside  the  backbone. 

Spores,  the  seed-like  particles  of  dust  produced  by  molds, 
bacteria,  and  other  plants. 

Sputum,  thick  mucus  removed  from  the  air  tubes. 

Sterilize,  to  kill  bacteria  in  a  substance  by  heating  it. 

Sternum,  the  breastbone. 

Stimulant,  a  substance  that  acts  upon  the  body  like  a  whip. 

Stomach,  the  bag  that  receives  food  after  it  is  swallowed. 

Sympathetic  system,  the  part  of  the  nervous  system  that  con- 
trols the  action  of  glands  and  involuntary  muscles. 

Synovial  fluid,  the  fluid  contained  in  the  joints. 

Tartar,  a  brown  substance  on  unbrushed  teeth. 

Tetanus,  lockjaw. 

Thermometer,  an  instrument  for  measuring  warmth. 

Thorax,  the  part  of  the  body  surrounded  by  the  ribs. 

Tissue,  a  collection  of  cells  having  a  special  work  to  do. 

Tonsillitis,  an  infectious  soreness  of  the  tonsils. 

Tonsils,  two  masses  of  flesh  growing  in  the  throat. 

Toxins,  poisons  formed  by  bacteria  and  disease  germs. 

Trachea,  the  air  tube  leading  to  the  lungs. 

Trachoma,  an  infectious  disease  of  the  eyelids. 

Triceps,  the  muscle  that  bends  the  elbow. 

Tuberculosis,  a  disease  in  which  white  bodies,  like  pinheads, 
form  in  the  flesh ;  consumption. 

Ulna,  the  bone  on  the  little  finger  side  of  the  forearm. 

Urea,  a  waste  substance  in  the  urine. 

Urine,  the  liquid  secreted  by  the  kidneys. 


GLOSSARY  377 

Vaccination,  protecting  the  body  against  smallpox  by  causing 

the  germs  of  cowpox  to  grow  in  the  body. 
Ventilation,  keeping  up  a  flow  of  f*sh  air  into  a  room. 
Ventricles,  the  two  cavities  in  the  lower  end  of  the  heart. 
Vermin,  insects  and  small  animals  that  are  troublesome  to  man. 
Villi,  the  small  projections  of  mucous  membrane  that  take  up 

food  from  the  intestine. 
Vocal  cords,  two  bands  of  flesh  by  means  of  which  the  sounds 

of  the  voice  are  formed. 

Wiggler,  a  young  mosquito  while  it  lives  in  the  water. 
Yeast,  microscopic  plants  that    change  sugar  to  alcohol  and 

carbon  dioxide. 


INDEX 


Absorbent  cotton,  293. 
Absorption,  231. 
Adenoids,  128,  342. 
Adulteration,  257. 
Air,  134. 
Albumin,  29. 
Alcohol,  46,  62. 

Effects  on  Arteries,  103. 

Brain,  331. 
,   Crime,  333. 

Diseases,  279. 

Excretion,  175. 

Food,  213. 

Heart,  103. 

Heat,  1 60. 

Insanity,  334. 

Kidneys,  176. 

Lungs,  122. 

Medicines,  62. 

Muscles,  85. 

Oxidation,  132. 

Poverty,  333. 

Strength,  85. 
Algae,  21. 
Anatomy,  16. 
Antiseptic,  284. 
Antitoxin,  275,  278. 
Aorta,  90. 
Appetite,  46. 

Arithmetic  problems,  134,  141,  146,  218. 
Artery,  90,  102. 
Artificial  respiration,  130. 
Assimilation,  234. 
Astigmatism,  349. 
Auricle,  96. 

Bacteria,  35,  149,  226,  263. 
Balanced  diet,  216. 
Bandage,.  1 10. 
Bathing,  166. 
Bedbugs,  207. 
Beer,  50. 


Bee  stings,  197. 
Biceps,  77. 
Bile,  224. 
Bleeding,  109. 
Blister,  163. 
Blood,  88,  97. 
Board  of  health,  43. 
Boils,  170. 
Bone,  64. 
Brain,  307,  318. 
Broken  bone,  113. 
Bronchi,  117. 
Butter,  247. 

Calorie,  213. 

Canning,  39. 

Capillaries,  93,  116,  231. 

Carbohydrates,  211. 

Carbolic  acid,  285. 

Carbon,  32. 

Carbon  dioxide,  32,  135. 

Cartilage,  70. 

Cells,  20,  69,  88,  119,  163,  309. 

Cereals,  240. 

Cerebellum,  319. 

Cerebrum,  320. 

Cesspool,  177. 

Cheese,  247. 

Churches,  366. 

Cider,  49. 

Cigarettes,  60. 

Cilia,  118. 

Circulation,  98. 

Clot,  88. 

Clothing,  155. 

Coagulation,  29. 

Coal  gas,  159. 

Cockroaches,  206. 

Cocoa,  248. 

Coffee,  248. 

Colds,  139,  156,  287. 

Cold  storage,  252. 


379 


38o 


INDEX 


Complexion,  165. 
Congestion,  167. 
Connective  tissue,  23,  69. 
Consciousness,  312. 
Consumption,  297. 
Convulsions,  113. 
Cooking,  258. 
Cornea,  346. 
Corpuscles,  88,  90. 
Cowpox,  276. 
Cream,  246. 
Cross-eye,  350. 

Dandruff,  170. 
Deafness,  342. 
Death  rate,  n. 
Decay,  37. 
Dermis,  162. 
Diaphragm,  119. 
Digestion,  222. 
Diphtheria,  278,  288. 
Disinfection,  283. 
Dislocation,  68. 
Distillation,  51. 
Drafts,  147. 
Dressings,  292. 
Drinking,  228. 
Drinking  cups,  193. 
Drugs,  62. 
Dumbness,  358. 
Dust,  148. 

Ear,  340. 
Eating,  227. 
Eggs,  245. 
Electric  shock,  132. 
Emulsion,  222. 
Epidemic,  12. 
Epidermis,  162. 
Epiglottis,  117. 
Epilepsy,  114. 
Esophagus,  222. 
Eustachian  tube,  342. 
Excretions,  173,  236,  282. 
Exercise,  81,  100. 
Eye,  346. 

Fainting,  113. 
Farsightedness,  349. 
Fat,  29,  211. 
Fermentation,  48. 


Fever,  153. 
Filtration,  191. 
Finger  prints,  164.     . 
Fire  department,  363. 
Fire  drill,  106. 
Fish,  245. 
Fits,  113. 
Fleas,  207. 
Flies,  181,  198. 
Focusing,  348. 
Food,  30,  211,  238. 
Formalin,  284. 
Fruit,  243. 
Fumigation,  286. 

Garbage,  181. 
Gas  trap,  180. 
Gastric  juice,  223. 
Glands,  24. 
Gymnasium,  85. 

Habits,  323. 
Hair,  168. 
Hearing,  340. 
Heart,  90,  95. 
Heat,  152. 
Hemoglobin,  89. 
Hookworm  disease,  290. 
Hospitals,  365. 
Humerus,  65. 
Hydrophobia,  42,  208. 
Hygiene,  16. 
Hysterics,  114. 

Ice,  192. 
Immunity,  275. 

Infectious  diseases,  35,  41,  270. 
Insanity,  330,  334. 
Intemperance,  47. 
Intestine,  175,  223. 
Intoxication,  53. 
Iris,  346. 

Joints,  65. 
Kidneys,  173. 

Lacteals,  233. 
Lactic  acid,  253. 
Larynx,  117. 
Lens,  347. 


INDEX 


Lice,  206. 

Periosteum,  72. 

Ligaments,  67. 

Peristalsis,  225. 

Lights,  159. 

Perspiration,  24,  154,  164 

Liver,  233. 

Pharynx,  222. 

Lockjaw,  294. 

Physiology,  16. 

Lungs,  1  1  6,  173. 

Pimples,  170. 

Lymph,  99,  163. 

Plague,  207. 

Plasma,  88. 

Maggots,  200. 

Playgrounds,  365. 

Malt,  50. 

Protein,  29,  211. 

Measles,  290. 

Ptomaines,  40. 

Meat,  243. 

Pulse,  97. 

Medulla,  319. 

Pupil,  346. 

Memory,  321. 

Microbes,  35. 

Quarantine,  285. 

Milk,  246,  253. 

Mind,  321. 

Rabies,  208. 

Minerals,  28. 

Radius,  65. 

Mineral  water,  186. 

Rats,  208. 

Mold,  38. 

Reflex  action,  313. 

Morphine,  60. 

Respiration,  116. 

Mosquitoes,  202. 

Rest,  328. 

Mouth,  263. 

Retina,  347. 

Mouth  breathing,  127. 

Rotting,  37. 

Mucous  membrane,  25. 

Round  shoulders,  82. 

Mucus,  25. 

Muscle,  76,  91. 

Sanatorium,  305. 

Scarlet  fever,  289. 

Nails,  170. 

Scrofula,  299. 

Narcotic,  55,  58. 

Secretion,  25. 

Nearsightedness,  349. 

Senses,  337. 

Nerves,  308. 

Septic  tank,  179. 

Nervousness,  325. 

Serum,  88. 

Nervous  system,  307. 

Sewage,  177,  363. 

Nicotine,  59. 

Sewer,  178. 

Nose,  263. 

Shock,  109. 

Nose  bleed,  112. 

Skeleton,  64. 

Nucleus,  23. 

Skin,  162. 

Sleep,  329. 

Opium,  60. 

Slipper  animalcule,  21. 

Organ,  19. 

Smell,  339. 

Osmosis,  231. 

Spectacles,  349. 

Oxidation,  31,  81,  132,  152,  213,  235. 

Speech,  358. 

Oxygen,  31. 

Spinal  cord,  307. 

Spitting,  300. 

Pancreas,  224. 

Spores,  39. 

Panic,  106. 

Sprain,  68. 

Papillae,  164. 

Starch,  211,  258. 

Paralysis,  310. 

Sterilize,  257. 

Paramecium,  21. 

Sternum,  119. 

Pasteurize,  257. 

Stews,  260. 

INDEX 


Stimulant,  54. 
Stomach,  223. 
Street  cleaning,  361. 
Sugar,  30,  211. 
Sunshine,  150,  284. 
Sunstroke,  155. 
Sweat,  24. 
Sweeping,  149. 
Swimming,  107. 
Sympathetic  system,  314. 
Synovial  fluid,  67. 

Tan,  162. 

Tartar,  268. 

Taste,  339- 

Tea,  248. 

Tears,  353. 

Teeth,  265. 

Tendon,  78. 

Tetanus,  294. 

Thermometer,  152. 

Thinking,  322. 

Thorax,  119. 

Tissues,  23. 

Tobacco,  58,  86,  103,  123,  334,  355. 

Tonsils,  129,  264. 

Touch,  337, 

Toxins,  270. 

Trachea,  117. 

Trachoma,  354. 


Triceps,  77. 
Tuberculosis,  297. 
Typhoid  fever,  291. 

Ulna,  65. 
Urea,  33. 
Uric  acid,  33. 
Urine,  174. 

Vaccination,  276. 
Vegetables,  242. 
Vein,  91. 
Ventilation,  144. 
Ventricle,  96. 
Vermin,  197. 
Villi,  234- 
Vinegar,  50. 
Vocal  cords,  357. 
Voice,  357. 

Water,  13,  28,  33,  187. 
Weather,  160,  273. 
Wells,  1 88. 

White  blood  cells,  90,  275. 
Whooping  cough,  290. 
Wigglers,  203. 
Wine,  48. 
Wounds,  292. 

Yeast,  48. 


^- 


IB  65536 


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